A hedge fund likely made a killing investing in a company right before Warren Buffett acquired it

Hedge fund manager Barry Rosenstein's Jana Partners likely made a killing on an investment in a company that Warren Buffett just acquired in a $37.2 billion mega-deal.

According to Jana's 13-F regulatory filing, the fund purchased 2,471,385 shares of Precision Castparts (PCP) in the second quarter ended June 30.

On Monday, August 10, Buffett's Berkshire Hathaway announced it was Precision Castparts where shareholders would get $235 per share in cash-an approximately 20% premium to the stock's closing price on Friday.

Hedge fund are required to disclose their long equity holdings in 13-F regulatory filings, which come out 45 days after the end of each quarter.

It is unclear how much Jana paid for the stake, or whether it is still holding it. It would be unusual for the fund to take such a large stake - Precision was Jana's 11th biggest equity holding at the end of the second quarter - and sell it in such short order.

The stock price hit a high of $220.22 in the second quarter, and is currently trading around $230, meaning that even if Jana bought at the second-quarter peak it would be up more than 4.5%.

Talk about great timing!

Here's a chart of the stock's performance during the second quarter timeframe:

Here's a chart of the stock's performance from the beginning of the second quarter through today: