Summary Prospectus by Investment Company (Form 497K)

SUMMARY PROSPECTUS

Lord Abbett Ultra Short Bond Fund

APRIL 1, 2026

CLASS/TICKER
CLASS A	LUBAX	CLASS F3	LUBOX	CLASS R6	LUBWX
CLASS A1	LUSNX	CLASS I	LUBYX
CLASS F	LUBFX	CLASS R5	LUBVX

Before you invest, you may want to review the Fund's prospectus and statement of additional information, which contain more information about the Fund and its risks. You can find the Fund's prospectus, statement of additional information and other information about the Fund at www.lordabbett.com/documentsandliterature. You can also get this information at no cost by calling 888-522-2388 (Option #2) or by sending an email request to [email protected]. The current prospectus and statement of additional information dated April 1, 2026 as may be supplemented from time to time, are incorporated by reference into this summary prospectus.

INVESTMENT OBJECTIVE

The Fund's investment objective is to seek current income consistent with the preservation of capital.

FEES AND EXPENSES

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. Information about sales charge discounts is available from your financial intermediary and in ''Sales Charge Reductions and Waivers'' on page 40 of the prospectus, Appendix A to the prospectus, titled ''Intermediary-Specific Sales Charge Reductions and Waivers,'' and ''Purchases, Redemptions, Pricing, and Payments to Dealers'' on page 9-1 of Part II of the statement of additional information (''SAI'').

Shareholder Fees(1)	(Fees paid directly from your investment)
Class		A	A1	F, F3, I, R5, and R6
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)		None(2)	1.50%	None
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)		None(3)	0.50%(4)	None

Annual Fund Operating Expenses
(Expenses that you pay each year as a percentage of the value of your investment)
Class	A	A1	F	F3	I
Management Fees	0.17%	0.17%	0.17%	0.17%	0.17%
Distribution and Service (12b-1) Fees	0.15%	0.25%	0.10%	None	None
Other Expenses	0.12%	0.12%	0.12%	0.07%	0.12%
Total Annual Fund Operating Expenses	0.44%	0.54%	0.39%	0.24%	0.29%

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Annual Fund Operating Expenses (continued)
(Expenses that you pay each year as a percentage of the value of your investment)
Class	R5	R6
Management Fees	0.17%	0.17%
Distribution and Service (12b-1) Fees	None	None
Other Expenses	0.12%	0.07%
Total Annual Fund Operating Expenses	0.29%	0.24%

(1)	A shareholder transacting in share classes without a front-end sales charge may be required to pay a commission to its financial intermediary. Please contact your financial intermediary for more information about whether such a commission may apply to your transaction.
(2)	Class A shares purchased directly are not subject to any front-end sales charge. However, Class A shares initially purchased without a front-end sales charge and subsequently exchanged for shares of another Lord Abbett Fund are subject to any applicable front-end sales charge.
(3)	Class A shares purchased directly are not subject to any contingent deferred sales charge ("CDSC"). However, Class A shares of the Fund that were obtained in exchange for Class A shares of another Lord Abbett Fund that were subject to CDSC of 1.00% at the time of exchange are subject to a CDSC unless the one-year CDSC period has expired or a CDSC waiver applies.
(4)	A CDSC of 0.50% may be assessed on certain Class A1 shares purchased or acquired without a sales charge if they are redeemed before the first day of the month in which the eighteenth month anniversary of the purchase falls.

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Class	If Shares Are Redeemed								If Shares Are Not Redeemed
	1 Year		3 Years		5 Years		10 Years		1 Year		3 Years		5 Years		10 Years
Class A Shares	$	45	$	141	$	246	$	555	$	45	$	141	$	246	$	555
Class A1 Shares	$	204	$	321	$	447	$	817	$	204	$	321	$	447	$	817
Class F Shares	$	40	$	125	$	219	$	493	$	40	$	125	$	219	$	493
Class F3 Shares	$	25	$	77	$	135	$	306	$	25	$	77	$	135	$	306
Class I Shares	$	30	$	93	$	163	$	368	$	30	$	93	$	163	$	368
Class R5 Shares	$	30	$	93	$	163	$	368	$	30	$	93	$	163	$	368
Class R6 Shares	$	25	$	77	$	135	$	306	$	25	$	77	$	135	$	306

Portfolio Turnover. The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in the annual fund operating expenses or in the example, affect the Fund's performance.

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During the most recent fiscal year, the Fund's portfolio turnover rate was 72% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund invests in various types of short duration, high quality, investment grade debt (or fixed income) securities. Under normal conditions, the Fund pursues its investment objective by investing at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in investment grade debt securities of various types. Under normal conditions, the Fund invests only in debt securities rated investment grade at the time of purchase or determined by Lord Abbett to be of comparable quality.

The Fund's investments consist of:

· corporate debt securities of U.S. issuers, including commercial paper;

· corporate debt securities of non-U.S. (including emerging market) issuers that are denominated in U.S. dollars;

· mortgage-backed, mortgage-related, and other asset-backed securities, including privately issued mortgage-related securities;

· securities issued or guaranteed by the U.S. Government, its agencies or instrumentalities; and

· structured securities and other hybrid instruments, including collateralized loan obligations ("CLOs").

The Fund seeks to manage interest rate risk through its management of the average effective duration of the securities it holds in its portfolio. The duration of a security takes into account the pattern of all expected payments of interest and principal on the security over time, including how these payments are affected by changes in interest rates. The longer a portfolio's duration, the more sensitive it is to interest rate risk. The shorter a portfolio's duration, the less sensitive it is to interest rate risk.

The maturity of a security is the length of time until final payment is due, or if applicable, an earlier date based on relevant factors such as maturity-shortening devices (e.g., call, put, pre-refunding, prepayment or redemption provisions, or an adjustable coupon). Normally, the Fund seeks to maintain an overall dollar-weighted average maturity of two years or less. Although the Fund invests in short-term debt securities, the Fund is not a money market fund and cannot guarantee that it will maintain a stable share price.

Under normal conditions, the Fund concentrates its investments in the financial services industry by investing more than 25% of its assets in securities issued by companies in the financial services industry. The Fund may, however, invest less than 25% of its assets in the financial services industry for temporary defensive purposes, as described in more detail below.

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The Fund may at times hold below investment grade securities (commonly referred to as "high-yield" or "junk" bonds) if the Fund purchased securities that were considered investment grade at their time of purchase and such securities subsequently are downgraded.

The investment grade debt securities described above may include mortgage-backed, mortgage-related, and other asset-backed securities, which directly or indirectly represent a participation in, or are secured by and payable from, mortgage loans, real property, or other assets. The Fund also may enter into repurchase agreements with maturities of less than 7 days. The Fund may invest in non U.S. dollar-denominated loans or securities.

Currently, the Fund expects to invest in derivatives including futures, options, and swaps. The Fund may use derivatives to attempt to hedge some of its investment risk on both a security- or portfolio-level basis, to manage portfolio duration, or for cash management purposes. For example, the Fund may invest in or sell short U.S. Treasury futures, securities index futures, other futures, and/or currency forwards to adjust the Fund's exposure to the direction of interest rates, or for other portfolio management reasons.

The portfolio management team buys and sells securities using a relative value-oriented investment process, meaning the portfolio management team generally seeks more investment exposure to securities believed to be undervalued and less investment exposure to securities believed to be overvalued. The portfolio management team combines top-down and bottom-up analysis to construct its portfolio, using a blend of quantitative and fundamental research. As part of its top-down analysis, the portfolio management team evaluates global economic conditions, including monetary, fiscal, and regulatory policy, as well as the political and geopolitical environment, in order to identify and assess opportunities and risks across different segments of the fixed income market. The portfolio management team employs bottom-up analysis to identify and select securities for investment by the Fund based on in-depth company, industry, and market research and analysis. The portfolio management team may actively rotate sector exposure based on its assessment of relative value. The Fund may engage in active and frequent trading of its portfolio securities.

The Fund may sell a security when the Fund believes the security is less likely to benefit from the current market and economic environment or shows signs of deteriorating fundamentals, among other reasons. The Fund may deviate from the investment strategy described above for temporary defensive purposes. The Fund may miss certain investment opportunities if defensive strategies are used and thus may not achieve its investment objective.

PRINCIPAL RISKS

As with any investment in a mutual fund, investing in the Fund involves risk, including the risk that you may receive little or no return on your investment. When you redeem your shares, they may be worth more or less than what you paid for

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them, which means that you may lose a portion or all of the money you invested in the Fund. The principal risks of investing in the Fund, which could adversely affect its performance, include:

· Portfolio Management Risk: If the strategies used and investments selected by the Fund's portfolio management team fail to produce the intended result, the Fund may suffer losses or underperform other funds with the same investment objective or strategies, even in a favorable market.

· Market Risk: The market values of securities will fluctuate, sometimes sharply and unpredictably, based on overall economic conditions, governmental actions or intervention, market disruptions caused by trade disputes, tariffs or other factors, political developments, and other factors. Prices of equity securities tend to rise and fall more dramatically than those of debt securities.

· Fixed Income Securities Risk: The Fund is subject to the general risks and considerations associated with investing in debt securities, including the risk that issuers will fail to make timely payments of principal or interest or default altogether. Lower-rated securities in which the Fund may invest may be more volatile and may decline more in price in response to negative issuer developments or general economic news due to their increased credit risk relative to other fixed-income investments. In addition, as interest rates rise, the Fund's investments typically will lose value. Fiscal, economic, monetary, or other governmental policies or measures have in the past-and may in the future-cause or exacerbate interest rate risks.

· Credit Risk: Debt securities are subject to the risk that the issuer or guarantor of a security may not make interest and principal payments as they become due or may default altogether. In addition, if the market perceives a deterioration in the creditworthiness of an issuer, the value and liquidity of securities issued by that issuer may decline. To the extent that the Fund holds below investment grade securities, these risks may be heightened. Insured debt securities have the credit risk of the insurer in addition to the credit risk of the underlying investment being insured.

· Interest Rate Risk: As interest rates rise, prices of bonds (including tax-exempt bonds) generally fall, typically causing the Fund's investments to lose value. Additionally, rising interest rates or lack of market participants may lead to decreased liquidity in fixed income markets. Interest rate changes generally have a more pronounced effect on the market value of fixed-rate instruments, such as corporate bonds, than they have on floating rate instruments, and typically have a greater effect on the price of fixed income securities with longer durations. A wide variety of market factors can cause interest rates to rise, including central bank monetary policy, rising inflation, and changes in general economic conditions.

· Liquidity/Redemption Risk: The Fund may lose money when selling securities at inopportune times to fulfill shareholder redemption requests. The risk of loss

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may increase depending on the size and frequency of redemption requests, whether the redemption requests occur in times of overall market turmoil or declining prices, and whether the securities the Fund intends to sell have decreased in value or are illiquid. The Fund may be less able to sell illiquid securities at its desired time or price. It may be more difficult for the Fund to value its investments in illiquid securities than more liquid securities.

· Concentration Risk: Because the Fund invests a significant portion of its assets in securities issued by companies in the financial services industry, developments affecting this industry may have a disproportionate impact on the Fund.

· Mortgage-Related and Other Asset-Backed Securities Risk: Mortgage-related securities, including commercial mortgage-backed securities ("CMBS") and other privately issued mortgage-related securities, and other asset-backed securities may be particularly sensitive to changes in prevailing interest rates and economic conditions, including delinquencies and defaults. The prices of mortgage-related and other asset-backed securities, depending on their structure and the rate of payments, can be volatile. They are subject to prepayment risk (higher than expected prepayment rates of mortgage obligations due to a fall in market interest rates) and extension risk (lower than expected prepayment rates of mortgage obligations due to a rise in market interest rates). These risks increase the Fund's overall interest rate risk. Some mortgage-related securities receive government or private support, but there is no assurance that such support will remain in place.

· Government Securities Risk: The Fund invests in securities issued or guaranteed by the U.S. Government or its agencies and instrumentalities (such as the Government National Mortgage Association ("Ginnie Mae"), the Federal National Mortgage Association ("Fannie Mae"), or the Federal Home Loan Mortgage Corporation ("Freddie Mac")). Different types of U.S. government securities are subject to different levels of credit risk, including the risk of default, depending on the nature of the particular government support for that security. Unlike Ginnie Mae securities, securities issued or guaranteed by U.S. Government-related organizations, such as Fannie Mae and Freddie Mac, are not backed by the full faith and credit of the U.S. Government and no assurance can be given that the U.S. Government would provide financial support. Past long-term U.S. credit rating downgrades have introduced greater uncertainty about the ability of the United States to repay its obligations. The value of the Fund's shares may be adversely affected by any future rating agency downgrades.

· Foreign and Emerging Market Company Risk: Investments in foreign companies and in U.S. companies with economic ties to foreign markets generally involve special risks. These companies may be more vulnerable to economic, political, and social instability and subject to less government supervision, lack of transparency, inadequate regulatory and accounting

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standards, and foreign taxes. Foreign company securities also include American Depositary Receipts ("ADRs"), which may be less liquid than the underlying shares in their primary trading market. Foreign securities also may subject the Fund's investments to changes in currency exchange rates. Emerging market securities generally are more volatile than other foreign securities, and are subject to greater liquidity, regulatory, and political risks. Investments in emerging markets may be considered speculative and generally are riskier than investments in more developed markets. Emerging markets are more likely to experience hyperinflation and currency devaluations. Securities of emerging market companies may have far lower trading volumes and less liquidity than securities of issuers in developed markets. In certain emerging market countries, governments participate to a significant degree in their respective economies. Action by these governments could have a significant adverse effect on market prices of securities and payment of dividends. Companies with economic ties to emerging markets may be susceptible to the same risks as companies organized in emerging markets.

· Collateralized Loan Obligations and Other Collateralized Obligations Risk: An investment in a CLO can be viewed as investing in (or through) another investment adviser and is subject to the layering of fees associated with such an investment. The risks of investing in a CLO generally can be summarized as a combination of economic risks of the underlying loans combined with the risks associated with the CLO structure governing the priority of payments, and include interest rate risk, credit risk, liquidity risk, prepayment risk, and the risk of default of the underlying asset, among others.

· Derivatives Risk: The risks associated with derivatives may be different from and greater than the risks associated with directly investing in securities and other investments. Derivatives may increase the Fund's volatility and reduce its returns. Derivatives may not perform as expected and the Fund may not realize the intended benefits. Whether the Fund's use of derivatives is successful may depend on, among other things, the portfolio managers' ability to correctly forecast market movements, company and industry valuation levels and trends, changes in foreign exchange and interest rates, and other factors. If the portfolio managers incorrectly forecast these and other factors, the Fund's performance could suffer. Derivatives are also subject to liquidity risk and the risk that the counterparty to a derivative transaction may fail to fulfill its contractual obligations under the derivative contract. In addition, given their complexity, derivatives are subject to the risk that improper or misunderstood documentation may expose the Fund to losses.

· Repurchase Agreement Risk: If the other party to a repurchase agreement defaults on its obligation under the agreement, the Fund may suffer delays and incur costs or lose money in exercising its rights under the agreement, or may be prevented from exercising such rights. If the seller fails to repurchase the security and the market value of the security declines, the Fund will lose money.

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An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. For more information on the principal risks of the Fund, please see the "More Information About the Fund - Principal Risks" section in the prospectus.

PERFORMANCE

The bar chart and table below provide some indication of the risks of investing in the Fund by illustrating the variability of the Fund's returns. Each assumes reinvestment of dividends and distributions. The Fund's past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.

The bar chart shows changes in the performance of the Fund's Class A shares from calendar year to calendar year. This chart does not reflect the sales charge applicable to Class A shares. If the sales charge were reflected, returns would be lower. Performance for the Fund's other share classes will vary due to the different expenses each class bears. Updated performance information is available at www.lordabbett.com or by calling 888-522-2388.

Bar Chart (per calendar year) - Class A Shares Best Quarter 2nd Q 2020 +2.14% Worst Quarter 1st Q 2020 -1.35%

The table below shows how the Fund's average annual total returns compare to the returns of a securities market index with investment characteristics similar to those of the Fund as well as to a broad-based securities market index.¹ The Fund's average annual total returns include applicable sales charges.

The after-tax returns of Class A shares included in the table below are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. In some cases, the return after taxes on distributions and sale of Fund shares may exceed the return before taxes due to a tax benefit resulting from realized losses on a sale of Fund shares at the end of the period that is used to offset other gains. Actual after-tax returns depend on an

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investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-advantaged arrangements such as 401(k) plans or Individual Retirement Accounts ("IRAs"). After-tax returns for other share classes are not shown in the table and will vary from those shown for Class A shares.

¹The Fund has adopted the Bloomberg U.S. Aggregate Bond Index as its broad-based securities market index.

Average Annual Total Returns
(for the periods ended December 31, 2025)
Class		1 Year	5 Years	Life of Class	Inception Date for Performance
Class A Shares					10/17/2016
	Before Taxes	4.81%	3.24%	2.56%
	After Taxes on Distributions	2.91%	1.92%	1.53%
	After Taxes on Distributions and Sale of Fund Shares	2.83%	1.91%	1.52%
Class A1 Shares		3.17%	2.83%	2.51%	7/31/2019
Class F Shares		4.87%	3.29%	2.61%	10/17/2016
Class F3 Shares		5.03%	3.45%	2.83%	4/4/2017
Class I Shares		4.97%	3.40%	2.72%	10/17/2016
Class R5 Shares		4.97%	3.40%	2.73%	10/17/2016
Class R6 Shares		5.03%	3.45%	2.77%	10/17/2016
Index
		4.30%	3.19%	2.36%	10/17/2016
ICE BofA U.S. Treasury Bill Index				2.47%	4/4/2017
(reflects no deduction for fees, expenses, or taxes)				2.73%	7/31/2019
		7.30%	-0.36%	1.62%	10/17/2016
Bloomberg U.S. Aggregate Bond Index				1.87%	4/4/2017
(reflects no deduction for fees, expenses, or taxes)				1.19%	7/31/2019

MANAGEMENT

Investment Adviser. The Fund's investment adviser is Lord, Abbett & Co. LLC ("Lord Abbett").

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Portfolio Managers

Portfolio Managers/Title	Member of the Portfolio Management Team Since
Yoana N. Koleva, Partner and Portfolio Manager	2016
Andrew H. O'Brien, Partner and Portfolio Manager	2016
Adam C. Castle, Partner and Head of Securitized Credit	2016

PURCHASE AND SALE OF FUND SHARES

The minimum initial and additional amounts shown below vary depending on the class of shares you buy and the type of account. Certain financial intermediaries may impose different restrictions than those described below. For Class I shares, the minimum investment shown below applies to certain types of institutional investors, but does not apply to registered investment advisers or retirement and benefit plans otherwise eligible to invest in Class I shares. See "Choosing a Share Class - Investment Minimums" in the prospectus for more information.

Investment Minimums - Initial/Additional Investments
Class	A(1)	A1	F, F3, R5, and R6	I
General and IRAs without Invest-A-Matic Investments	$1,500/ No minimum	$1,500/ No minimum	N/A	$1 million/ No minimum
Invest-A-Matic Accounts(2)	$250/$50	$250/$50	N/A	N/A
IRAs, SIMPLE and SEP Accounts with Payroll Deductions	No minimum	N/A	N/A	N/A
Fee-Based Advisory Programs and Retirement and Benefit Plans	No minimum	N/A	No minimum	No minimum
(1) There is no investment minimum for Class A shares purchased by investors maintaining an account with a financial intermediary that has entered into an agreement with Lord Abbett Distributor LLC ("Lord Abbett Distributor") to offer Class A shares through a load-waived network or platform, which may or may not charge transaction fees. (2) There is no minimum initial investment for Invest-A-Matic accounts held directly with the Fund, including IRAs.

You may sell (redeem) shares through your securities broker, financial professional or financial intermediary on any business day the Fund calculates its net asset value ("NAV"). If you have direct account access privileges, you may redeem your shares by contacting the Fund in writing at Lord Abbett Funds Service Center, P.O. Box 534489, Pittsburgh, PA 15253-4489 (regular mail) or Attention: 534489, 500 Ross Street 154-0520, Pittsburgh, PA 15262 (overnight mail), by calling 888-522-2388 or by accessing your account online at www.lordabbett.com.

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TAX INFORMATION

The Fund's distributions, if any, generally are taxable to you as ordinary income, capital gains or a combination of the two, unless you are a tax-exempt investor or investing through a tax-advantaged arrangement, such as a 401(k) plan or an IRA. Any withdrawals from such a tax-advantaged arrangement may be taxable to you.

PAYMENTS TO BROKER-DEALERS AND OTHER FINANCIAL INTERMEDIARIES

If you purchase Fund shares through a broker-dealer or other financial intermediary (such as a bank), the Fund and the Fund's distributor or its affiliates may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other financial intermediary and your individual financial professional to recommend the Fund over another investment. Ask your individual financial professional or visit your financial intermediary's website for more information.

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NOTES:

Investment Company Act File Number: 811-07988
			USB-7SUM (04/26)