Warren Buffett's Berkshire Hathaway Inc. slashed its exposure to big-bank shares in the first quarter, liquidating its position in Citigroup Inc. and trimming positions in $Bank of America Corp(BAC-N)$. and $Capital One Financial Corp(COF-N)$., according to a regulatory filing on Thursday.

Berkshire sold 14,639,502 Citigroup (C) shares, according to the 13F filing with the Securities and Exchange Commission. The filing said Berkshire sold 48,660,056 shares of Bank of America $(BAC.SI)$, cutting its stake by over 7%; it continued to hold more than 631.5 million shares as of March 31. Berkshire cut its stake in Capital One by 300,000 shares, or around 4%.

Berkshire's biggest buy of the quarter was Constellation Brands Inc. $(STZ)$, acquiring 6,384,676 shares, increasing its holdings by more than 113% to a total of 12,009,000 shares.

Apple Inc. $(AAPL)$ remained Berkshire's single largest holding at 300 million shares, making up around 25% of the company's total equity portfolio. Berkshire had previously significantly cut its Apple stake but made no moves in the first quarter, according to the filing.

Large investors are required to file 13-F forms 45 days after the end of each calendar quarter detailing long positions. They tend to be closely followed for clues to moves by major investors, though the information they provide is dated and not necessarily complete. Filers aren't required to reveal short positions and the positions that are reported may or may not be parts of larger trades.

Buffett earlier this month shocked Berkshire shareholders $(BRK.A)$ $(BRK.B)$, announcing he would step down as chief executive at the end of the year to hand the reins to his designated successor Greg Abel. Buffett will remain chairman of the conglomerate.