Dislike: Facebook shares fell 4.5 percent to $179.37 Friday after the social-media giant said that it is revamping its system to show fewer posts from brands and fewer videos in favor of more posts from friends and family. The changes may result in people spending less time on Facebook.

No go: Shares of GoPro plunged 25 percent to $5.67 Monday after it said revenue fell sharply last quarter. The company said it had to slash prices on cameras to drive more sales, and its $340 million in fourth-quarter revenue fell far short of Wall Street's expectations. The shares closed Friday at $6.23.

Chip flip: Micron Technology shares dropped 4.2 percent to $43.62 Tuesday a day after announcing an end to its partnership with Intel to develop chips, in what Micron described as "forging our own paths." Micron shares closed Friday at $42.81.

Kodak moment: Shares of Eastman Kodak more than doubled to $6.80 Tuesday after it said it is getting into the digital licensing and cryptocurrency market. The companies are launching blockchain technology with KodakOne and KodakCoin. Kodak shares closed Friday at $9.20.

Taking off: United Continental shares rose 6.3 percent to $72.79 Wednesday after the airline said a key revenue trend last quarter was better than forecast. It credited stronger demand and fares. United closed Friday at $78.40.

Lost shine: Signet Jewelers fell 7.2 percent to $52.50 Wednesday after it reported weaker sales for the holiday season than a year earlier. E-commerce business grew by a "double-digit" percentage. Signet shares closed Friday at $56.94.

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