*By Kristen Lee* Stocks closed sharply lower on Friday, closing out a roller-coaster week on Wall Street. The Dow Jones Industrial Average closed nearly 300 points lower, while the S&P lost 1.7 percent and the Nasdaq ended down 2.1 percent. Early Friday, the Dow plunged by as much as 539 points, before paring its losses after authorities announced the arrest of a man in connection with the mail bombing of prominent Democrats. Cesar Sayoc, Jr., a 56-year-old Florida resident lives in Aventura and has a criminal record, according to the Broward County Sheriff. Art Hogan, chief market strategist at B. Riley FBR, said a "mixed bag" of earnings ー and specifically, weak guidance from bellwether tech companies Amazon and Alphabet ー are weighing on the markets. Amazon's ($AMZN) closed about 8 percent lower on Friday after it posted better-than-expected earnings, but fell short on revenue and guidance. Google parent Alphabet ($GOOGL) ended the day nearly 2 percent lower after reporting a jump in profits but also indicated slowing growth. "In this earnings season, with a market that's very nervous about a whole host of things, you have to hit all three: you have to get your earnings right, your revenue right, and you have to give upbeat guidance ー and when you don't, especially in the case of either Amazon or Alphabet, you're in trouble," Hogan said Friday in an interview on Cheddar. He said the mail bomb threat transfixing the nation is also having an impact. Every significant case of terrorism, and especially domestic terrorism, has cast a pall over the markets and prompted many to stop making investment decisions, Hogan added. "It puts everybody in a very nervous place," he said. "And \[until\] we get answers, it's very difficult to have a robust feeling about what's going on in the economy and the markets."
