Microsoft said Thursday that an accounting adjustment to reflect a weak online ad business led to its first quarterly loss in its 26 years as a public company. The software company had warned that it was taking a $6.2 billion charge because its 2007 purchase of online ad service aQuantive hasn’t yielded the returns envisioned by management. The non-cash adjustment is something companies do when the value of their assets decline. Microsoft Corp. paid $6.3 billion for aQuantive, only to see rival Google Inc. expand its share of the online ad market. The charge led to a $492 million loss in the April-June quarter, or 6 cents a share. That compares with earnings of $5.9 billion, or 69 cents, a year ago. Read the full story at USA Today.