I’ve been a little late - okay, a lot late - to weigh in on the ongoing auction of online ad company DoubleClick, which is controlled by private equity firm Hellman and Friedman. Supposedly, the company is looking for at least $2 billion. The current owners paid $1.1 billion in 2005, and subsequently sold off a few of the original pieces.. Among the rumored suitors: Google (GOOG), Microsoft (MSFT) and Time Warner’s (TWX) AOL unit.

Youssef Squali, Internet analyst at Jefferies & Co. asserts in a research note that the losers in the auction will likely shop elsewhere. One candidate would be a privately held company called Right Media, which auctions off online ad space; although he points out that the obvious buyer for that one would be Yahoo (YHOO), which already holds a 20% stake.

Other potential targets, in Squali’s view, include aQuantive (AQNT), ValueClick (VCLK) and 24/7 Real Media (TFSM). “Bottom line, the sale of DoubleClick is likely to spur the large players into action, driving up valuations for the group as a whole.”

Actually, all three stocks have been on the rise. Since mid-March, 24/7 is up 15%; ValueClick is up 7% and aQuantive is up almost 9%. So I would say, “let the bidding begin,” but it looks like it already has.