Unfriended: LinkedIn shares declined 44 percent Friday to $108.38 after the professional networking site forecast a year of slower revenue growth amid signs of weakness in sales of advertising and marketing tools.

New tech titan: Alphabet, the recently formed parent company of Google, rose 4 percent Tuesday to $784.08 after the company's results handily beat analysts' forecasts late Monday, fueled by a booming advertising business that's supporting ambitious new projects. Alphabet closed the week at $683.57.

Health care mergers: Shares of Alere jumped 45 percent to $54 Monday after Abbott Laboratories announced it was purchasing the company focused on dialogistics for $5.8 billion. Alere shares closed the week at $ 53.20. Abbott shares, which fell 0.3 percent to $37.72 Monday, closed Friday at $37.41.

Cutbacks: Yahoo slumped 7 percent, to $27.12 Wednesday after the company announced it would cut 1,700 jobs and sell some of the company's struggling businesses. Shares closed the week at $27.97.

Twitter chatter: Twitter jumped 8 percent, $18.20 Monday following reports that the company is in talks with private equity firms to possibly acquire or invest in the Internet company. Shares finished the week at $15.72.

Delicious: Food processor Tyson Foods rose 10 percent to $57.10 Friday after the company raised its full-year forecast.

Off camera: Mobile video camera maker GoPro plunged 13 percent to $9.29 Thursday after reporting a wider-than-expected quarterly loss as sales dropped 31 percent. GoPro shares closed Friday at $9.96.

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