UPDATE 2-Berkshire to become BofA's top shareholder after share swap

* Berkshire to exercise warrants for 700 mln BofA shares

* BofA shares up 1.1 percent (Adds details, BofA's share value, share price movement)

June 30 (Reuters) - Warren Buffett's Berkshire Hathaway Inc will swap its preferred shares in Bank of America Corp into common shares worth about $17 billion, making it the biggest shareholder of lender.

Berkshire said on Friday it would exercise its warrants for 700 million common shares of Bank of America following a dividend increase by the lender to 12 cents per share.

Bank of America's shares were up 1.1 percent in premarket trading on Friday.

The second-largest U.S. bank boosted its annual dividend on Wednesday to 48 cents per share from 30 cents, beginning in the third quarter, after its plan to return capital was approved by the Federal Reserve under its annual "stress test" program.

Buffett had bought $5 billion of Bank of America preferred stock with a 6 percent dividend, or $300 million annually, in August 2011, when investors worried about the bank's capital needs.

The purchase included warrants to acquire 700 million common shares at $7.14 each, less than one-third of Thursday's closing price of $24.32.

If Omaha, Nebraska-based Berkshire made the swap now, it would have a paper profit of about $12 billion and begin collecting $336 million of annual dividends, on top of roughly $1.7 billion of dividends already paid.

Buffett's move underscores his confidence in Brian Moynihan, Bank of America's chief executive.

Moynihan has worked to restore investors' confidence in his Charlotte, North Carolina-based bank after it spent more than $70 billion since the global financial crisis to resolve legal and regulatory matters, largely from its purchases of Countrywide Financial Corp and Merrill Lynch & Co.

Berkshire, which is also Wells Fargo & Co's biggest shareholder, said it expected to use the preferred shares to fund the acquisition.

Vanguard Group, which is currently BofA's biggest shareholder, holds 6.6 percent stake, or about 652 million shares in the company. (Reporting By Aparajita Saxena in Bengaluru; Editing by Anil D'Silva)