UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-Q

or

Commission file number 1-8972

INDYMAC BANCORP, INC.

(Exact name of registrant as specified in its charter)

(Registrant’s telephone number, including area code)

(800) 669-2300

      Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.     Yes þ          No o

      Indicate by check mark whether the registrant is an accelerated filer (as defined in Rule 12b-2 of the Exchange Act).     Yes þ          No o

      Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date.

Common stock outstanding as of April 20, 2005: 62,475,789 shares

FORM 10-Q QUARTERLY REPORT

For the Period Ended March 31, 2005

TABLE OF CONTENTS

FORWARD-LOOKING STATEMENTS

      This Form 10-Q contains statements that may be deemed to be forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Forward-looking statements include statements regarding our projected financial condition and results of operations, plans, objectives, future performance and business. Forward-looking statements typically include the words “anticipate,” “believe,” “estimate,” “expect,” “project,” “plan,” “forecast,” “intend,” “goal,” “target” and other similar expressions. These statements reflect our current views with respect to future events and financial performance. They are subject to risks and uncertainties that could cause future results to differ materially from historical results or from the results anticipated. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of their dates or as of the date hereof if no other date is identified. We undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. For further information on our key operating risks, refer to “Key Operating Risks” beginning on page 56 and to IndyMac’s annual report on Form 10-K for the year ended December 31, 2004.

      References to “IndyMac Bancorp” or the “Parent Company” refer to the parent company alone while references to “IndyMac,” the “Company,” or “we” refer to IndyMac Bancorp, Inc. and its consolidated subsidiaries. References to “IndyMac Bank” or the “Bank” refer to our subsidiary IndyMac Bank, F.S.B. and its consolidated subsidiaries. The following discussion addresses the Company’s financial condition and results of operations for the three months ended March 31, 2005.

HIGHLIGHTS FOR THE QUARTER

      Highlights for the quarters ended March 31, 2005, March 31, 2004 and December 31, 2004, were as follows:

OVERALL RESULTS

      IndyMac Bancorp first quarter results reflected continued strong operating fundamentals. The Company achieved a new record of production of $12.0 billion, an increase of 67% over the first quarter 2004 and an increase of 3% from the prior record achieved in the fourth quarter of 2004. Based on this record production and the mortgage industry volume published by Mortgage Bankers Association on April 14, 2005, our mortgage industry market share increased to 2.0%.⁽¹⁾ In addition to the strong production results, our net interest and gain on sale margins also strengthened during the quarter resulting in record quarterly earnings per share of $1.01, an increase of 44% from $0.70 per share in the first quarter of 2004 and an increase of 11% from the pro forma earnings per share of $0.91 in the fourth quarter of 2004. Included in operating expenses during the quarter was a $6 million pretax legal charge for the settlement of a previously disclosed class action lawsuit involving employee classification and overtime matters. During the first quarter of 2005, the Company continued to deploy capital to facilitate balance sheet growth and achieved record total assets of $18.0 billion as of March 31, 2005.

OUR BUSINESS

      IndyMac is the holding company for IndyMac Bank®, the largest savings and loan or savings bank in Los Angeles and the 10th largest thrift nationwide (based on assets). IndyMac is in the business of designing, manufacturing, and distributing cost-efficient financing for the acquisition, development, and improvement of single-family homes. IndyMac also provides financing secured by single-family homes to facilitate consumers’ personal financial goals and strategically invests in single-family mortgage related assets. We facilitate the acquisition, development, and improvement of single-family homes through our award-winning e-MITS® (Electronic Mortgage Information and Transaction System) platform that automates underwriting, risk-based pricing and rate locking on a nationwide basis via the Internet at the point of sale. IndyMac Bank offers highly competitive mortgage products and services that are tailored to meet the needs of both consumers and mortgage professionals.

      For this quarter, we have realigned our segments from the previous four operating segments structure based on products and customers to two primary operating segments, the mortgage banking and the thrift segments. They more clearly highlight our hybrid thrift/mortgage banking business model and are consistent with the way we manage and evaluate our business. Additionally, we moved the retained assets and loan servicing division to become a part of our mortgage banking segment because we believe the ability to service

mortgage loans is an integral part of our mortgage banking business. These segment results depict our profitability by channel of origination. Each channel’s results include the impact of intercompany transactions between channels, which are elimination in consolidation. Additionally, these segment changes provide clear transparency to the two primary activities in our hybrid model: mortgage banking with high asset turn and high returns on equity, and thrift investing characterized by lower but more consistent returns on equity. Prior period segment results have been revised to conform to this new presentation.

      The mortgage banking segment offers many types of home mortgage products, predominantly prime, to our customers using a technology-based approach across multiple channels on a nationwide basis. Our broad product line includes adjustable-rate mortgages (“ARMs”) offering borrowers multiple payment options, fixed-rate mortgages, both conforming and non-conforming, subprime mortgage loans and reverse mortgages. Our largest production channel, mortgage professionals, originates or purchases mortgage loans through its relationships with mortgage brokers, mortgage bankers, and financial institutions. We also offer mortgages and reverse mortgages to consumers through channels such as direct mail, Internet leads, online advertising, affinity relationships, real estate professionals, including Realtors, and through our Southern California retail banking branches. This segment generally provides higher returns on invested equity than the thrift segment through quicker asset turnover. We sell the majority of the mortgage loans originated or purchased by this segment on an on-going basis in the secondary market, and to a lesser extent may transfer loans to our thrift segment. In conjunction with the sale of mortgage loans, we generally retain the right to continue to perform the mortgage loan servicing function on behalf of the investors in the loans sold for a specified servicing fee plus late fees and any reinvestment income (mortgage servicing rights or MSRs). We also retain, to a lesser degree than MSRs, certain other servicing-related assets including AAA-rated interest-only securities, prepayment penalty securities associated with prepayment charges on the underlying mortgage loans, non-investment grade securities and residual securities from the sale of mortgage loans. To hedge the prepayment risk embedded in these assets, we use a combination of several financial instruments such as U.S. Treasury securities, principal-only securities, agency debentures, futures, floors, swaps, or options to protect the value of these assets. The principal sources of revenue for the mortgage banking segment include gain on sale of mortgage loans, fee income and net interest income during the period loans are held pending sale and service fee income related to the MSRs.

      In an effort to diversify and stabilize company-wide earnings, mitigate, to an extent, the cyclicality of our mortgage banking segment, and leverage our capital and infrastructure as a nationwide mortgage lender and an FDIC-insured financial institution, we allocate capital to invest in certain of our mortgage loan products and other specialty mortgage products and commercial loans in our thrift segment. The focus of this segment is the generation of core stable net interest income to provide a return on invested capital with minimum threshold returns established for various types of investments based on the underlying risks of the investments. The principal investments in this segment include single-family residential (“SFR”) mortgage loans (predominantly prime ARMs), construction financing for single-family residences or lots provided directly to individual consumers, builder construction financing facilities for larger residential subdivision loans, home equity lines of credit (“HELOCs”), and mortgage-backed securities. Additionally, beginning in 2005, we have reentered the warehouse lending business, which provides short-term revolving warehouse lending facilities to small-to-medium size mortgage bankers and brokers to finance mortgage loans from the closing of the loans until they are sold. The thrift segment leverages the mortgage banking segment’s infrastructure as a source for much of its investments. Revenues generated by the thrift segment are primarily net interest income on loans and securities, and to a lesser extent, gain on sale of loans and service fee income on HELOCs.

      The following tables summarize the Company’s financial results for the three months ended March 31, 2005, illustrating the revenues earned by its two primary segments via each of its operating channels. The profitability of each operating channel is measured on a fully-leveraged basis after allocating capital based on regulatory capital rules.

      Operating channels that originate mortgage loans are credited with gain on sale at funding based on the estimated fair value. Any difference between the actual gain on sale realized and the estimate is credited or charged to the operating channel in the period the loan is sold or transferred to the held for investment portfolio. Differences between the gain on sale credited to the operating channels and the consolidated gain on

sale due to timing of loan sales or transfers to the held for investment portfolio are eliminated in consolidation. The Company uses a funds transfer pricing (“FTP”) system to allocate interest income and expense to the operating channels. Each operating channel is allocated funding with maturities and interest rates matched with the expected lives and repricing frequencies of the channel’s assets. The difference between these allocations and the Company’s actual net interest income and capital levels resulting from centralized management of funding costs is reported in the Treasury unit. Corporate overhead costs related to managing the Company as a whole are not allocated to the operating channels.

      The following table summarizes the segment financial highlights for the three months ended March 31, 2005: