Apple Inc. AAPL on Friday asked employees at its 12,000-person Apple Park campus in Silicon Valley to work from home if possible because of coronavirus risks. It is also asking workers in the Seattle area to work from home. The company's retail stores in Santa Clara County remain open. There were 20 confirmed cases of the coronavirus in the county as of March 5, health officials said. Several other tech companies have encouraged employees to work from home this week, including Alphabet Inc. GOOGL GOOG, Microsoft Corp. MSFT, Amazon.com Inc. AMZN, Facebook Inc. FB, Twitter Inc. TWTR, and HP Inc. HPQ because of fears around the coronavirus.