NEW YORK (CNNMoney.com) - Has Warren Buffet found his next big acquisition and will he let the world know about it this weekend?

According to a published report Friday, speculation is building that the billionaire investor may do just that during the annual meeting of his holding company, Berkshire Hathaway Inc.

What is Warren Buffett's next big acquisition?

The Wall Street Journal reported that Wall Street is abuzz with anticipation of a big announcement from the 75-year-old investment guru at the upcoming annual shareholders meeting, set for Saturday in Omaha, Neb.

Berkshire (Research) has built up a cash pile of $45 billion and Buffett has said more than once that he wants to spend billions of dollars in the energy and utilities sectors, the paper said.

"I suspect when we get to Omaha. we'll learn something of his acquisition pipeline, which is likely to be very fertile right now," Glenn Tongue, a longtime Berkshire shareholder and a managing partner of hedge fund T2 Partners LLC, was quoted as saying.

In the past four months, Buffett has agreed to buy Russell Corp., a branded-clothing manufacturer, Applied Underwriters, a workers' compensation insurer, and Business Wire, an electronic news distributor -- deals of several million dollars each, the paper said.

Berkshire's last big buy - a $5.1 billion deal announced in May 2005 to buy Pacific Corp., an Oregon utility company - is expected to close in the coming weeks, the report said.

Last June, Buffett said he planned to spend more than $15 billion in the U.S. energy sector, with future acquisitions in the power sector likely to be done through Berkshire's MidAmerican Holdings subsidiary, the report said.

One company that might fit well into that plan is PG&E Corp., a San Francisco utility with a market value of $13 billion, the paper said. A spokesman for PG&E declined to comment, the paper said.

In the insurance sector, analysts have pointed to Mercury General Corp., a Los Angeles automotive insurer, as an attractive target, the Journal said.

And Reinsurance - insurance for other insurers - is another favorite for Berkshire, which already operates several such businesses, including National Indemnity, Berkshire Hathaway Reinsurance Group and General Re, the report said.

Buffett declined to discuss the speculation, the Journal said.

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