In the video below, Foolish financial analyst Matt Koppenheffer takes a look at Berkshire Hathaway (BRK.B 0.91%) and why it may not be so easy for Warren Buffett and company to make a big acquisition anytime soon.

Buffett likes to talk about pulling out the old elephant gun when he wants to make a purchase. Last time he did so, in November 2009, Berkshire bagged a big one: Burlington Northern railroad.

It was a near-ideal time to do so, Matt says. Since that time, the S&P 500 index is up 45%. Meanwhile, CSX (CSX 0.81%), a comparable company to Burlington, is up 72%. CSX's profits have climbed, and the multiple that investors are willing to pay for the company has grown. Matt says we can assume the same for Burlington.

But things are different today. We've had a huge rally in the markets. There are still sectors that may be undervalued, but it's going to be tough for Buffett to find the type of value he looks for in a large, publicly traded company, Matt says.

Investors may need to be patient and wait for the market to soften, Matt says.