Reprieve: A bullish hiring report helped the stocks of technology companies, banks, health care and industrial companies notch strong gains Friday. Twitter shares gained 7 percent to $29.95. Microsoft rose 4.6 percent to $101.93. Deere gained 5.3 percent to $151.68.

iFlop: Apple's stock plunged 9.7 percent to $142.46 Thursday after warning that its iPhone sales in China weakened over the holidays, coming in well short of expectations and adding to investors' fears that the global economy is losing strength. Apple shares closed the week at $148.26.

Tech angst: Chipmakers and suppliers of phone parts closed down sharply Thursday on Apple news. Skyworks Solutions fell 8.8 percent to $61.94 on the day and closed the week at $63.63. Qorvo gave up 9.5 percent to $55.37 on the news, ending Friday at $59.37.

Good hire: Square Inc. shares rose 11 percent to $58.18 Friday after it selected an Activision Blizzard executive as chief financial officer. The CFO position is especially critical at Square because founder and Chief Executive Jack Dorsey simultaneously serves as CEO of Twitter Inc.

Coming up short: Tesla shares dropped 7 percent to $309.38 Wednesday after the electric carmaker cut U.S. prices for all its vehicles and fell short on deliveries of its mass-market Model 3 sedans in the fourth quarter. The stock closed Friday at $317.69.

Trade woes: Caterpillar gave up 2.6 percent to $123.06 Thursday amid continuing concerns over cooling China demand and higher costs for metals as a result of tariffs. Caterpillar closed Friday at $128.15.