NEW YORK ( TheStreet) -- Chipmaker Advanced Micro Devices ( AMD) fell 4.5% in pre-market trading Tuesday to $8.82 after CEO Dirk Meyer resigned. The company said Meyer had resigned in mutual agreement with the board. Current Chief Financial Officer Thomas Seifert was named interim CEO. Microsoft ( MSFT) was up 0.39% to $28.33 in pre-market trading, after Bob Muglia, the president of its server and tools business, would be leaving the company. Muglia is the latest in a string of top Microsoft executives who have left the company within the last year, including chief software architect Ray Ozzie and business division president Stephen Elop. Skype, which launched video calling on its iPhone several days ago, reached a new milestone of 27 million users online at the same time, according to GigaOM. The company, which acquired mobile video start-up Qik last week, is looking to boost its video presence. Mobile payments company Square has raised $27.5 million in new venture funding. The investment quadruples Square's valuation, according to the Wall Street Journal. Founded by Twitter co-founder Jack Dorsey, Square allows users to accept credit card payments using their mobile phones. Bump Technologies, a mobile app company that lets people bump their phones together to enhance contact information, has raised $16.5 million in its second round of venture funding, the company said Tuesday. The investment was led by prominent venture capital firm Andreessen Horowitz. --Written by Olivia Oran in New York. >To follow the writer on Twitter, go to http://twitter.com/Ozoran. >To submit a news tip, send an email to: firstname.lastname@example.org.