* Berkshire raises stake in J&J, US Bancorp, Wells

* lowers holding of ConocoPhillips, Constellation Energy

* Berkshire shares unchanged after market
(Adds details on holdings, analyst comment, background,
byline)

By Lilla Zuill

NEW YORK, May 15 (Reuters) - Warren Buffett's Berkshire
Hathaway Inc (BRKa.N: Quote, Profile, Research) (BRKb.N: Quote, Profile, Research) said on Friday it had modestly
raised its stake in health-care company Johnson & Johnson
(JNJ.N: Quote, Profile, Research), and also bumped up ownership of US Bancorp (USB.N: Quote, Profile, Research) and
Wells Fargo (WFC.N: Quote, Profile, Research), two banks the billionaire has been bullish
about.

Berkshire disclosed that as of March 31 it had added 3.9
million shares of J&J, 1.5 million shares of U.S. Bancorp and
12.4 million more Wells shares. The company is Wells' largest
shareholder.

Berkshire also bought more shares of two railroads --
Northern Santa Fe Corp (BNI.N: Quote, Profile, Research) and Union Pacific Corp (UNP.N: Quote, Profile, Research) --
but reduced its ownership of energy company stocks.

"The changes were not dramatic," said Morningstar analyst
Bill Bergman. "They did not do a lot here, which probably
reflects that he is seeing more opportunity in bond markets."

The value of Berkshire's portfolio as of March 31 was
unchanged at about $51.87 billion.

The company disclosed a lower stake in oil company
ConocoPhillips (COP.N: Quote, Profile, Research). Buffett said earlier this month that
ownership of Conoco had fallen further since the end of March.
He has referred to Berkshire's roughly $7 billion investment in
Conoco as a major mistake.

The company also cut its holding of Constellation Energy
(CEG.N: Quote, Profile, Research) and of UnitedHealth Group (UNH.N: Quote, Profile, Research), and sold all the
Ingersoll Rand (IR.N: Quote, Profile, Research) and Iron Mountain (IRM.N: Quote, Profile, Research) shares it had
owned.

Berkshire disclosed its holdings in a U.S. Securities and
Exchange Commission filing.

The quarterly report excludes holdings on non-U.S.
exchanges. It may also exclude other investments for which
Buffett has received SEC permission to not immediately
disclose.

The regulator sometimes lets Buffett delay disclosure so
investors cannot copy him while he is buying.

Berkshire's Class A shares closed down $480, or 0.54
percent, at $89,120. Its Class B shares also fell to $2,899.80,
a 0.67 percent decline.

Berkshire shares have slid about 40 percent from their
52-week high last Sept. 19.

They also remain far below their record $151,650 set in
December 2007.

Berkshire has been hurt in recent quarters by the falling
value of its stock investments, as well as long-term derivatives
contracts tied to stock market indexes and the credit quality of
junk bonds. It disclosed its first quarterly loss since 2001 in
the first quarter.
(Reporting by Lilla Zuill, editing by Matthew Lewis)