Updated from 6:15 p.m., May 15

Warren Buffett's

Berkshire Hathaway

(BRK.A) - Get Report

bought banks -- the relatively liquid ones, that is -- and sold energy in the first quarter.

According to its 13-K filing with the

Securities and Exchange Commission

, the company added substantially to common-share stakes in

US Bancorp

(USB) - Get Report

,

Wells Fargo

(WFC) - Get Report

,

Johnson & Johnson

(JNJ) - Get Report

and

Burlington Northern

(BNI)

and sharply cut back on holdings of

Constellation Energy

(CEG)

,

ConocoPhillips

(COP) - Get Report

and

Carmax

(KMX) - Get Report

.        

The market value of Berkshire's stock portfolios fell 21% to $40.87 billion as of March 31, according to the filing.

Berkshire added nearly 12 million shares to its stake in Wells Fargo and about 1.5 million to its stake in US Bancorp, which now stands about 69 million shares. Berkshire bought about 4 million shares of Johnson & Johnson in the quarter, increasing its ownership to nearly 32.5 million shares.

The company pared its Constellation Energy holdings to 14.8 million shares from about 20 million. Carmax, meanwhile, went from 17.6 million to 12 million shares.

ConocoPhillips has been a thorn in Berkshire's side. Losses on trades in the oil concern's stock cost Berkshire nearly $2.75 billion in 2008. After cutting its stake in Conoco by 7 million shares, Berkshire now holds about 63.3 million.

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