Following are the US stocks that were actively trading in the Monday morning session. The stocks include Global Crossing, American Medical Systems, Level 3 and Community Health Systems.

Gainers

Global Crossing Limited (NASDAQ: GLBC) shares were up 55 percent, $8.13, to $22.93 after it agreed to be acquired by Level 3 Communications, Inc. (NASDAQ: LVLT) for about $1.9 billion in stock.

Shares of American Medical Systems Holdings (NASDAQ: AMMD) surged 32 percent, or $7.17, to $29.50 after it agreed to be bought by Endo Pharmaceuticals (NASDAQ:ENDP) for $2.9 billion.

Shares of Level 3 Communications, Inc. (NASDAQ: LVLT) after it struck a deal to buy Global Crossing Limited (NASDAQ: GLBC) for about $1.9 billion stock deal to boost its service portfolio.

Endo Pharmaceuticals (NASDAQ:ENDP) shares gained 6 percent to $43.16 after its deal to buy American Medical Systems Holdings (NASDSAQ: AMMD).

Shares of Biogen Idec Inc. (NASDAQ:BIIB) were up 6 percent, or $3.99, to $77.28 after its multiple sclerosis drug met goals in a late-stage study.

Losers

Community Health Systems, Inc. (NYSE: CYH) shares plunged 36 percent, or $14.46, to $25.84 after Tenet Healthcare (NYSE:THC) sued the hospital operator for overbilling insurers. Community Health Systems has been trying to buy Tenet Healthcare.

Tenet Healthcare (NYSE:THC) shares also fell 15 percent, or $1.17, to $6.38 after its lawsuit against Community Health Systems.

Shares of 3D Systems Corp.(NASDAQ: TDSC) were down 11 percent, or $6.15, to $50.37. During the past 52-weeks, the stock has been trading between $11.10 and $58.70.