UPDATE 1-Sirius XM plans to adopt poison pill

* Sirius poison pill sets 4.9 pct ownership trigger

* Seeks shareholder approval before June 30, 2010

* Sirius' net operating loss gives tax benefits

NEW YORK, April 29 (Reuters) - U.S. satellite radio provider
Sirius XM Radio Inc (SIRI.O), which is 40 percent controlled by
Liberty Media (LINTA.O), plans to adopt a shareholder-rights
plan that makes hostile takeovers more difficult.

Under the plan -- known as a poison pill -- if any person or
group buys 4.9 percent or more of Sirius' outstanding shares of
common stock without the approval of the board, a significant
dilution in the voting and economic ownership of the investor
would occur, Sirius said on Wednesday.

The plan exempts future acquisitions of common stock by
Liberty Media's Liberty Radio LLC.

Analysts have said that Sirius, which was targeted by
EchoStar Corp (SATS.O) earlier this year, could be an attractive
acquisition from a tax perspective because its net operating
losses can be carried forward to help offset taxes against
future profits.

"Our net operating loss carry-forwards are an important
asset of the company; an asset that we believe we should make
every effort to protect," said Sirius Chief Executive Mel
Karmazin. "The rights plan is intended to enhance stockholder
value; it has not been implemented for defensive or
anti-takeover purposes."

Denver-based Liberty Media, controlled by cable pioneer John
Malone, agreed to lend $530 million to Sirius in February in
exchange for a 40 percent equity stake, saving the debt-laden
satellite radio provider from possible bankruptcy.

The deal came after Charlie Ergen's satellite TV company
EchoStar had tried to take over Sirius XM by snapping up
hundreds of millions of dollars of its debt. [ID:nN17352330]

"It looks to me like Liberty is going to make sure no one
else can dilute their majority stake or otherwise take control
of Sirius so they have access to the NOL (net operating loss),"
said Kaufman Bros analyst Todd Mitchell.

Sirius said its board has approved the shareholder-rights
plan, which will be submitted for a stockholder vote by June 30,
2010. If stockholders do not approve the rights plan by this
date, it will terminate.

The rights plan will last until Aug. 1, 2011, unless
terminated by the board, Sirius said.

Liberty could not immediately be reached for comment.

Shares of Sirius were flat at 39.5 cents in extended
trading.
(Reporting by Yinka Adegoke and Tiffany Wu, editing by Matthew
Lewis)