Berkshire Hathaway Discloses A Stake in HP; Shares Soar Almost 10%

HP shares increased 9.9 percent to $38.38 in after-hours trading on Berkshire's disclosure of the interest in SEC filings.

HP, headquartered in Palo Alto, California, has about 1.06 billion outstanding shares as of Jan. 31.

HP and Berkshire Hathaway did not immediately reply to calls for comment.

HP is Berkshire's third significant investment since Feb. 26, when Buffett said in his annual shareholders letter that "internal prospects provide far higher returns than acquisitions" and that stock markets "excite us little."

Berkshire agreed to acquire insurance business Alleghany (NYSE:Y) Corp for $11.6 billion in cash on March 21, bolstering its portfolio of insurers, which already includes Geico.

Berkshire previously disclosed a 14.6 percent position in Occidental Petroleum Corp (NYSE:OXY), a holding that cost well over $6 billion to acquire.

Buffett had gone six years without making a significant acquisition, leaving Berkshire with $146.7 billion in cash and equivalents. Buffett has vowed to maintain a cash reserve of at least $30 billion.

Berkshire did not specify whether the HP share is owned by Buffett or his portfolio managers Todd Combs and Ted Weschler, despite the fact that Buffett typically manages bigger assets.

Buffett is primarily responsible for Berkshire Hathaway's position in Apple Inc (NASDAQ:AAPL), which he refers to as one of the "Big Four" firms that account for the majority of the value of his Omaha, Nebraska-based conglomerate.

Berkshire's insurers, the BNSF railroad, and Berkshire Hathaway (NYSE:BRKa) Energy round up the "Big Four."