Updated from 4:25 p.m. EST

Stocks ended higher as several high-profile acquisitions convinced investors that corporate America was shaking off its doldrums.


Dow Jones Industrial Average gained 81 points, or 0.82%, to 9892, while the

Nasdaq was up 34 points, or 1.75%, to 19878, and the

S&P 500 was gaining 11 points, or 1%, to 1134.

In the day's biggest deal,


(AMGN) - Get Report

said it will buy rival



for cash and stock worth about $30 a share, or $16 billion altogether. The acquisition would give Amgen, already the world's biggest biotech company, access to Immunex's rheumatoid arthritis treatment Enbrel. Amgen gained $3.38, or 6.03%, to $59.41 while Immunex tacked on $3.45, or 13.5% to $29.07.

Also Monday,


(V) - Get Report

confirmed it will exchange cash and stock worth $10.3 billion for the entertainment assets of

USA Networks

(USAI) - Get Report

. The deal calls for the establishment of a new company, Vivendi Universal Entertainment, to be headed by USA chief Barry Diller. Vivendi closed up $3.23, or 6.6%, to $52.18 while USA Networks added 95 cents to $24.77.

A bidding war broke out over the weekend for

P&O Princess Cruise Lines


, which previously agreed to a friendly merger with fellow cruise operator

Royal Caribbean

(RCL) - Get Report



(CCL) - Get Report

entered the fray with a hostile $4.5 billion offer that P&O rejected, citing among other things greater "regulatory risk" in Europe and the U.S. P&O's shares rose $1.26 to $22.30, while Royal Caribbean's stock lost $1.94 to $14.39. Carnival was off 43 cents to $26.87.

The yen touched a three-year low against the dollar and two-year low against the euro after a Japanese government official's comment suggested the country wouldn't support the currency at current levels. The yen "is in a phase to correct its level, which was too strong" given the economic outlook, Japanese Vice Finance Minister Haruhiko Kuroda said, according to



European stocks rose sharply, with London's FTSE 100 up 1.5% to 5136 and Germany's Xetra DAX up 3.5% to 5080. In Japan, the Nikkei fell 1.8% to 10,323, while Hong Kong's Hang Seng was unchanged at 11,466.

In London, crude oil futures were down about 2% after OPEC said planned production cuts might be delayed.

At 4 p.m. EST Treasury issues were weaker with the 10-year note off 4/32 to 98 15/32, yielding 5.20%.