Dimon, in a letter to shareholders with the company's new annual report on Wednesday, said the company is "not a conglomerate" and is "not necessarily" more risky because of its size. The bank is facing tougher capital requirements from regulators than its rivals and has seen analysts ask whether its returns to shareholders would be better if it were broken up.

The threat of additional regulatory and legal costs being imposed on the company are holding down the value of JPMorgan stock and have led to it trade at lower price-earnings ratio than some of its competitors, Dimon lamented in the letter.

Dimon has stepped up his public statements defending the company's business model since December when the Federal Reserve unveiled pending requirements that the biggest banks, and JPMorgan in particular, hold more capital to protect against losses. A report from a Goldman Sachs analyst in early January then spelled out how the bank might be worth more if broken up.

In his letter on Wednesday, Dimon argued that JPMorgan has the same three basic businesses as regional U.S. banks -consumer banking, commercial banking, and asset management-plus one more, its global corporate and investment bank. The investment bank allows the bank to go further and serve big U.S. corporations doing business abroad, he said.

"Our mix of businesses works for clients-and for shareholders," Dimon wrote.

"Large does not necessarily mean complex," he said.

The company, Dimon said, has added about 8,000 people to improve legal compliance by the bank and its employees.

JPMorgan now has more than 300 employees working on risk models. The team completed over 500 model reviews in 2014 and implemented a system to check the ongoing performance of more than 1,000 complex models, Dimon said.

The letter, which covers 37 pages with text and graphics, also includes a commentary on stress tests of banks by the Federal Reserve. Dimon said he supports the testing, but he argued that JPMorgan would weather the downturns envisioned by the Fed "far better" that the regulator estimated. JPMorgan would be more aggressive cutting expenses than the Fed assumed and it would reduce its trading risks as a crisis developed, he said.

(Reporting by David Henry in New York; Editing by Chris Reese, Bernard Orr)