Lord Abbett
Quarterly Portfolio Holdings Report

Lord Abbett
Developing Growth Fund

For the period ended October 31, 2023

Schedule of Investments (unaudited)

October 31, 2023

Investments	Shares		Fair Value
LONG-TERM INVESTMENTS 96.98%
COMMON STOCKS 96.98%
Aerospace & Defense 3.68%
AeroVironment, Inc.*		417,140	$	47,829,273
Axon Enterprise, Inc.*		138,480		28,317,775
Total				76,147,048
Beverages 1.30%
Celsius Holdings, Inc.*		176,171		26,793,847
Biotechnology 8.60%
Arcellx, Inc.*		757,429		26,699,372
Bridgebio Pharma, Inc.*		625,177		16,279,609
Cytokinetics, Inc.*		551,990		19,242,372
Immunovant, Inc.*		310,940		10,276,567
Karuna Therapeutics, Inc.*		66,261		11,039,745
Krystal Biotech, Inc.*		383,313		44,797,790
Natera, Inc.*		428,657		16,919,092
Nuvalent, Inc. Class A*		354,904		18,486,949
Xenon Pharmaceuticals, Inc. (Canada)*(a)		457,227		14,174,037
Total				177,915,533
Broadline Retail 1.86%
Global-e Online Ltd. (Israel)*(a)		1,094,039		38,411,709
Building Products 3.47%
AAON, Inc.		395,764		21,561,223
Hayward Holdings, Inc.*		1,421,246		14,923,083
Trex Co., Inc.*		628,250		35,313,932
Total				71,798,238
Capital Markets 1.07%
Piper Sandler Cos.		158,673		22,190,419
Commercial Services & Supplies 3.95%
Clean Harbors, Inc.*		124,689		19,160,959
MSA Safety, Inc.		221,782		35,014,942
Tetra Tech, Inc.		182,738		27,576,991
Total				81,752,892

Investments	Shares		Fair Value
Communications Equipment 1.26%
Extreme Networks, Inc.*		1,265,059	$	26,085,517
Construction & Engineering 5.04%
Comfort Systems USA, Inc.		226,050		41,107,192
EMCOR Group, Inc.		195,310		40,360,812
Sterling Infrastructure, Inc.*		312,702		22,780,341
Total				104,248,345
Diversified Consumer Services 2.71%
Duolingo, Inc.*		383,065		55,946,643
Electrical Equipment 2.39%
EnerSys		76,456		6,543,104
NEXTracker, Inc. Class A*		469,267		16,311,721
nVent Electric PLC (United Kingdom)(a)		551,074		26,523,192
Total				49,378,017
Energy Equipment & Services 1.47%
TechnipFMC PLC (United Kingdom)(a)		1,413,311		30,414,453
Entertainment 1.26%
Roku, Inc.*		435,543		25,945,297
Financial Services 6.73%
AvidXchange Holdings, Inc.*		2,852,990		24,649,833
Flywire Corp.*		1,623,449		43,654,544
Remitly Global, Inc.*		2,629,786		70,820,137
Total				139,124,514
Food Products 0.69%
Freshpet, Inc.*		248,840		14,283,416
Ground Transportation 3.05%
Saia, Inc.*		96,451		34,576,719
XPO, Inc.*		375,476		28,464,836
Total				63,041,555

See Notes to Schedule of Investments. 1

Schedule of Investments (unaudited)(continued)

October 31, 2023

Investments	Shares		Fair Value
Health Care Equipment & Supplies 4.73%
Glaukos Corp.*		582,238	$	39,708,632
iRhythm Technologies, Inc.*		140,941		11,066,687
RxSight, Inc.*		761,286		16,854,872
Shockwave Medical, Inc.*		100,898		20,811,222
TransMedics Group, Inc.*		248,471		9,312,693
Total				97,754,106
Health Care Providers & Services 0.64%
Guardant Health, Inc.*		508,081		13,149,136
Hotels, Restaurants & Leisure 2.34%
Cava Group, Inc.*(b)		502,995		15,889,612
Shake Shack, Inc. Class A*		200,989		11,263,424
Wingstop, Inc.		116,590		21,309,154
Total				48,462,190
Leisure Products 1.07%
YETI Holdings, Inc.*		521,495		22,173,967
Life Sciences Tools & Services 1.59%
10X Genomics, Inc. Class A*		402,217		14,190,216
Pacific Biosciences of California, Inc.*		1,364,427		8,432,159
Quanterix Corp.*		468,278		10,170,998
Total				32,793,373
Media 0.85%
Integral Ad Science Holding Corp.*		1,535,517		17,627,735
Personal Care Products 4.04%
BellRing Brands, Inc.*		653,727		28,587,482
elf Beauty, Inc.*		272,432		25,235,376
Inter Parfums, Inc.		155,453		19,759,631
Oddity Tech Ltd. Class A (Israel)*(a)(b)		385,797		9,857,113
Total				83,439,602

Investments	Shares		Fair Value
Pharmaceuticals 2.35%
Intra-Cellular Therapies, Inc.*		438,176	$	21,803,638
Structure Therapeutics, Inc. Add ADR*		251,644		18,697,149
Ventyx Biosciences, Inc.*		562,853		8,116,340
Total				48,617,127
Professional Services 1.61%
Upwork, Inc.*		869,858		9,090,016
Verra Mobility Corp.*		1,222,170		24,162,301
Total				33,252,317
Semiconductors & Semiconductor Equipment 3.88%
Aehr Test Systems*		393,411		9,268,763
Allegro MicroSystems, Inc.*		467,267		12,130,251
Axcelis Technologies, Inc.*		100,054		12,756,885
Rambus, Inc.*		847,793		46,060,594
Total				80,216,493
Software 21.69%
Agilysys, Inc.*		244,307		20,959,097
Appfolio, Inc. Class A*		145,007		27,198,963
Appian Corp. Class A*		263,021		10,378,809
Confluent, Inc. Class A*		1,404,180		40,594,844
CyberArk Software Ltd. (Israel)*(a)		212,613		34,791,991
Descartes Systems Group, Inc. (Canada)*(a)		264,616		19,107,921
DoubleVerify Holdings, Inc.*		591,906		16,472,744
Five9, Inc.*		171,857		9,945,365
Freshworks, Inc. Class A*		1,539,573		27,619,940
Gitlab, Inc. Class A*		372,952		16,141,363
Guidewire Software, Inc.*		182,165		16,418,531
JFrog Ltd. (Israel)*(a)		879,440		19,778,606
Manhattan Associates, Inc.*		112,962		22,025,331

2 See Notes to Schedule of Investments.

Schedule of Investments (unaudited)(continued)

October 31, 2023

Investments	Shares		Fair Value
Software (continued)
Monday.com Ltd. (Israel)*(a)		163,115	$	21,203,319
Qualys, Inc.*		134,548		20,579,117
Samsara, Inc. Class A*		1,742,700		40,204,089
SPS Commerce, Inc.*		146,107		23,426,796
Tenable Holdings, Inc.*		792,512		33,372,680
Varonis Systems, Inc.*		839,913		28,254,673
Total				448,474,179
Technology Hardware, Storage & Peripherals 1.30%
Super Micro Computer, Inc.*		112,240		26,878,113
Textiles, Apparel & Luxury Goods 0.96%
Deckers Outdoor Corp.*		33,083		19,752,536
Trading Companies & Distributors 1.40%
SiteOne Landscape Supply, Inc.*		210,692		29,027,037
Total Common Stocks (cost $1,940,494,628)				2,005,095,354
	Principal Amount
SHORT-TERM INVESTMENTS 2.49%
Repurchase Agreements 1.42%
Repurchase Agreement dated 10/31/2023, 2.800% due 11/1/2023 with Fixed Income Clearing Corp. collateralized by $29,963,100 of U.S. Treasury Note at 5.000% due 10/31/2025; value: $29,938,521; proceeds: $29,353,739 (cost $29,351,456)	$	29,351,456		29,351,456

Investments	Shares		Fair Value
Money Market Funds 0.96%
Fidelity Government Portfolio(c) (cost $19,934,213)		19,934,213	$	19,934,213
Time Deposits 0.11%
CitiBank N.A.(c) (cost $2,214,913)		2,214,913		2,214,913
Total Short-Term Investments (cost $51,500,582)				51,500,582
Total Investments in Securities 99.47% (cost $1,991,995,210)				2,056,595,936
Other Assets and Liabilities – Net 0.53%				11,027,537
Net Assets 100.00%			$	2,067,623,473

ADR	American Depositary Receipt.
*	Non-income producing security.
(a)	Foreign security traded in U.S. dollars.
(b)	All or a portion of this security is temporarily on loan to unaffiliated broker/dealers.
(c)	Security was purchased with the cash collateral from loaned securities.

See Notes to Schedule of Investments. 3

Schedule of Investments (unaudited)(concluded)

October 31, 2023

The following is a summary of the inputs used as of October 31, 2023 in valuing the Fund’s investments carried at fair value⁽¹⁾:

Investment Type(2)	Level 1		Level 2		Level 3		Total
Long-Term Investments
Common Stocks	$	2,005,095,354	$	–	$	–	$	2,005,095,354
Short-Term Investments
Repurchase Agreements		–		29,351,456		–		29,351,456
Money Market Funds		19,934,213		–		–		19,934,213
Time Deposits		–		2,214,913		–		2,214,913
Total	$	2,025,029,567	$	31,566,369	$	–	$	2,056,595,936

(1)	Refer to Note 2(b) for a description of fair value measurements and the three-tier hierarchy of inputs.
(2)	See Schedule of Investments for fair values in each industry and identification of foreign issuers and/or geography. When applicable, each Level 3 security is identified on the Schedule of Investments along with the valuation technique utilized.

A reconciliation of Level 3 investments is presented when the Fund has a material amount of Level 3 investments at the beginning or end of the period in relation to the Fund’s net assets.

4 See Notes to Schedule of Investments.

Notes to Schedule of Investments (unaudited)

1. ORGANIZATION  

Lord Abbett Developing Growth Fund, Inc. (the “Fund”) is registered under the Investment Company Act of 1940, as amended (the “Act”), as a diversified, open-end management investment company. The Fund was incorporated under Maryland law on August 21, 1978. The Fund’s predecessor corporation was organized on July 11, 1973.

The Fund’s investment objective is long-term growth of capital through a diversified and actively managed portfolio consisting of developing growth companies, many of which are traded over the counter.

2. SIGNIFICANT ACCOUNTING POLICIES 

(a)	Investment Valuation-Under procedures approved by the Fund’s Board of Directors (the “Board”), the Board has designated the determination of fair value of the Fund’s portfolio investments to Lord, Abbett & Co. LLC (“Lord Abbett”) as its valuation designee. Accordingly, Lord Abbett is responsible for, among other things, assessing and managing valuation risks, establishing, applying and testing fair value methodologies, and evaluating pricing services. Lord Abbett has formed a Pricing Committee that performs these responsibilities on behalf of Lord Abbett, administers the pricing and valuation of portfolio investments and ensures that prices utilized reasonably reflect fair value. Among other things, these procedures allow Lord Abbett, subject to Board oversight, to utilize independent pricing services, quotations from securities and financial instrument dealers and other market sources to determine fair value.
	Securities actively traded on any recognized U.S. or non-U.S. exchange or on The NASDAQ Stock Market LLC are valued at the last sale price or official closing price on the exchange or system on which they are principally traded. Events occurring after the close of trading on non-U.S. exchanges may result in adjustments to the valuation of foreign securities to reflect their fair value as of the close of regular trading on the New York Stock Exchange. When valuing foreign equity securities that meet certain criteria, the Pricing Committee uses a third-party fair valuation service that values such securities to reflect market trading that occurs after the close of the applicable foreign markets of comparable securities or other instruments that correlate to the fair-valued securities. Unlisted equity securities are valued at the last quoted sale price or, if no sale price is available, at the mean between the most recently quoted bid and ask prices.
	Securities for which prices are not readily available are valued at fair value as determined by the Pricing Committee. The Pricing Committee considers a number of factors, including observable and unobservable inputs, when arriving at fair value. The Pricing Committee may use related or comparable assets or liabilities, recent transactions, market multiples, book values, and other relevant information to determine the fair value of portfolio investments. The Board or a designated committee thereof periodically reviews reports that may include fair value determinations made by the Pricing Committee, related market activity, inputs and assumptions, and retrospective comparison of prices of subsequent purchases and sales transactions to fair value determinations made by the Pricing Committee.
	Short-term securities with 60 days or less remaining to maturity are valued using the amortized cost method, which approximates fair value. Investments in open-end money market mutual funds are valued at their NAV as of the close of each business day.

5

Notes to Schedule of Investments (unaudited)(continued)

(b) Fair Value Measurements-Fair value is defined as the price that the Fund would receive upon selling an investment or transferring a liability in an orderly transaction to an independent buyer in the principal or most advantageous market of the investment. A three-tier hierarchy is used to maximize the use of observable market data and minimize the use of unobservable inputs and to establish classification of fair value measurements for disclosure purposes. Inputs refer broadly to the assumptions that market participants would use in pricing the asset or liability, including assumptions about risk - for example, the risk inherent in a particular valuation technique used to measure fair value (such as a pricing model) and/or the risk inherent in the inputs to the valuation technique. Inputs may be observable or unobservable. Observable inputs reflect the assumptions market participants would use in pricing the asset or liability. Observable inputs are based on market data obtained from sources independent of the reporting entity. Unobservable inputs reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Unobservable inputs are based on the best information available in the circumstances. The three-tier hierarchy classification is determined based on the lowest level of inputs that is significant to the fair value measurement, and is summarized in the three broad Levels listed below:

●	Level 1 –	unadjusted quoted prices in active markets for identical investments;
●	Level 2 –	other significant observable inputs (including quoted prices for similar investments, interest rates, prepayment speeds, credit risk, etc.); and
●	Level 3 –	significant unobservable inputs (including the Fund’s own assumptions in determining the fair value of investments).
A summary of inputs used in valuing the Fund’s investments as of October 31, 2023 and, if applicable, Level 3 rollforwards for the period then ended is included in the Fund’s Schedule of Investments.
Changes in valuation techniques may result in transfers into or out of an assigned level within the three-tier hierarchy. The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

3. FEDERAL TAX INFORMATION  

It is the policy of the Fund to meet the requirements of Subchapter M of the Internal Revenue Code applicable to regulated investment companies and to distribute substantially all taxable income and capital gains to its shareholders. Therefore, no income tax provision is required.

The Fund files U.S. federal and various state and local tax returns. No income tax returns are currently under examination. The statute of limitations on the Fund’s filed U.S. federal tax returns remains open generally three years after the filing of the tax return. The statute of limitations on the Fund’s, state and local tax returns may remain open for an additional year depending upon the jurisdiction.

4. SECURITIES LENDING AGREEMENT  

The Fund has established a securities lending agreement with Citibank, N.A. for the lending of securities to qualified brokers in exchange for securities or cash collateral equal to at least the market value of securities loaned, plus interest, if applicable. Cash collateral is invested in an approved money market fund. In accordance with the Fund’s securities lending agreement, the

6

Notes to Schedule of Investments (unaudited)(concluded)

market value of securities on loan is determined each day at the close of business and any additional collateral required to cover the value of securities on loan is delivered to the Fund on the next business day. As with other extensions of credit, the Fund may experience a delay in the recovery of its securities or incur a loss should the borrower of the securities breach its agreement with the Fund or the borrower becomes insolvent at a time when the collateral is insufficient to cover the cost of repurchasing securities on loan.

The initial collateral received by the Fund is required to have a value equal to at least 100% of the market value of the securities loaned. The collateral must be marked-to-market daily to cover increases in the market value of the securities loaned (or potentially a decline in the value of the collateral). In general, the risk of borrower default will be borne by Citibank, N.A.; the Fund will bear the risk of loss with respect to the investment of the cash collateral. The advantage of such loans is that the Fund continues to receive income on loaned securities while receiving a portion of any securities lending fees and earning returns on the cash amounts which may be reinvested for the purchase of investments in securities.

As of October 31, 2023, the market value of securities loaned and collateral received for the Fund were as follows:

Market Value of Securities Loaned	Collateral Received
$21,577,005		$22,149,126

7

QPHR-DEV-1Q
(12/23)