Warren Buffett: I don't have the investment opportunities I used to

Warren Buffett is currently speaking with CNBC's Becky Quick after he released his 50th letter to Berkshire Hathaway shareholders on Saturday.

Among the topics Buffett addressed is the investing challenges Buffett currently faces, and whether it is easier to invest now than it was 20 or 30 years ago.

In response, Buffett didn't say if it was easier, but said he now has a different investing problem: size.

"If we're going to buy 5% of a company," Buffett said, "to make that purchase worth 1% of Berkshire, it has to be a $2 billion company ... and if the stock doubles Berkshire makes 0.5%."

In other words, the size of Berkshire makes the opportunities for Buffett to see a dramatic increase in his wealth, or the value for Berkshire Hathaway shareholders, more sparse because of the company's size.

Last week, we highlighted comments from Buffett made 50 years ago about the size of the hedge fund he was then running, which he worried was getting too big.

Berkshire is now a massive conglomerate with a market cap over $300 billion. So, that problem certainly hasn't eased at all.

Follow our complete coverage of Buffett's conversation on CNBC here.