Microsoft moved one step nearer to its full-force entry into the online advertising market Friday, when a federally mandated waiting period expired.

In May, Microsoft agreed to buy online advertiser aQuantive for $6 billion. Federal Trade Commission regulations call for a waiting period to examine any possible antitrust implication, and the deadline passed Friday without comment.

aQuantive, a digital marketing services company, is heavily involved in creating and tracking Internet advertising campaigns. Microsoft cast its gaze toward the Seattle-based company after losing out on several other advertising companies, most notably DoubleClick, which arch-rival Google agreed to buy for $3.1 billion in April. The same month, Microsoft's other search competition, Yahoo, bought advertising company Right Media.