WPP is reportedly discussing a takeover of 24/7 Real Media – although it is only one of a number of suitors we understand to be encircling the online ad company.

The New York Post reports that 24/7 is ‘on the auction block’ and could end up fetching more than $600m, with WPP already in talks.

If that’s true, though, WPP will face stiff competition as several big media companies have been stung into action by the recent Google-DoubleClick deal, and its implications for the search and display ad markets. 

We understand that the likes of Sky, Viacom, Yahoo! and Microsoft are involved in the race for 24/7 – but that its options also include a tie-up with one of the big search engines in Asia.

WPP chief executive Martin Sorrell also recently expressed fears over Google’s DoubleClick acquisition, saying:

“It raises issues as to whether we are happy to let Google have our client’s data and our own data which Google could use for its own purposes in contextual and targeted advertising.”

Sorrell’s firm pulls in roughly the same annual revenues as Google, though its market capitalisation is much lower, perhaps partly due to the fact that Google owns Google.com, which has to be one of the most valuable web properties around.

Will 24/7 be the next firm to face consolidation in a sector that continues to grow? Don’t bet against it.