Warren Buffett has a $128 billion cash pile. Wall Street can't figure out why he isn't spending it.

• Berkshire Hathaway revealed when it reported third-quarter earnings Saturday that its cash pile had grown to a record $128.2 billion, even though it repurchased $700 million of its own shares.
• Wall Street isn't sure why the company isn't spending more of the money on share buybacks. Berkshire Hathaway also hasn't made a major acquisition since January 2016.
• Here's what four analysts said about Berkshire Hathaway's record cash pile.
• Read more on Business Insider.

On Saturday, Berkshire Hathaway revealed in its third-quarter earnings release that the company's cash pile has ballooned to a new record.

The company, run by Warren Buffett, now has $128.2 billion in cash on hand. That's up from the $122.4 billion it had at the end of the second quarter, and a more than fivefold increase from the $23 billion the company held in 2009.

That pile grew even though Berkshire Hathaway repurchased $700 million of its own shares during the third quarter, leading Wall Street analysts from UBS, Morgan Stanley, CFRA and more to question why the company didn't repurchase more of its own stock.

"We remain surprised that the company has not been more aggressive with share repurchase," a team of UBS analysts led by Brian Meredith wrote in a Monday note.

Berkshire Hathaway loosened its rule around share buybacks in 2018, making it easier for Buffett and Charlie Munger, Berkshire Hathaway's vice chair, to authorize buybacks when the repurchase price is "below Berkshire's intrinsic value," according to the company.

But it appears that the leaders of the company aren't fully taking advantage of the new rule - under the looser guidelines, Berkshire Hathaway could've repurchased as much as $200 million more of its own stock this quarter, according to UBS.

The firm also hasn't made an acquisition since January 2016, when it finalized the purchase of Precision Castparts, a manufacturing company, for $32 billion, according to the Wall Street Journal. In a 2018 letter to shareholders, Buffett said he hoped to invest more of Berkshire's cash, but was having trouble finding deals because "prices are sky-high for businesses possessing decent long-term prospects."

That's not to say that the company hasn't made large investments - it has. In April, Buffett joined Occidental Petroleum's bid for Anadarko, offering his own $10 billion investment for the $38 billion bid for the oil company. Buffett also holds large amounts of top company stocks, including shares of Apple, Bank of America, Coca-Cola, and Kraft Heinz.

Here's what four analysts said about Warren Buffett's burgeoning cash pile.