eBay's New Ad Exchange Raises A Question: What If It Acquired Online Ad Giant Rubicon?

eBay has opened another private ad exchange, this time in Australia, to serve advertisers who want to target people shopping on the auction site. This exchange follows the ones opened earlier in the U.S. and in the U.K. The U.K. and Australian exchanges are powered by Rubicon Project, the web ad giant that supplies much of the "plumbing" in the adtech world.

Ad exchanges work by allowing advertisers to bid in an auction on web users arriving on a site, in this case eBay. The users arrive carrying tracking cookies — little bits of software code — that detail the user's browsing history. That gives advertisers an idea of what the users are interested in — and therefore how valuable they might be as ad targets. eBay's advantage over regular media ad sales publishers is that everyone arriving on the site is already in the mood for shopping.

The extended eBay-Rubicon partnership led AdExchanger to ask, "One can't help but wonder - is Rubicon Project a likely acquisition target for Ebay?"

Such a tie-up would be huge — in some months, Rubicon's ads are seen by more internet users than Google's are.

We can't add anything to that ... except to note that Rubicon CEO Frank Addante has recently been seen carrying an interesting deck around New York describing Rubicon's capabilities. And, of course, we told you back in January that strategic moves of the M&A/IPO variety were being mulled at the company. (Yahoo was a previous potential suitor linked to Rubicon also, but that rumor seems to have died.)

The Australian eBay exchange will offer advertisers 7 million uniques per month and 1 billion impressions. eBay claims it will be Australia's largest private real-time bidding marketplace.

eBay's ad exchange ambitions appear to place it in direct competition with Amazon, which has ramped up its own exchange recently. Both sites, of course, serve shoppers — and are therefore of keen interest to advertisers.

Read more about eBay's exchanges here and here.

Disclosure: Jeff Bezos is an investor in Business Insider through his personal investment company Bezos Expeditions.