AOL has put in a $900 million bid - one that analysts say needs sweetening - on TradeDoubler, a Sweden-based European provider of online marketing and sales solutions, in a buy that would expand AOL's ad abilities abroad, according to paidContent.

However, the deal needs 90 percent shareholder approval, and Alecta, a Swedish pension group that claims 10.1 percent ownership of TradeDoubler, reportedly has rejected the bid, reports the E-Commerce Times.

The deal has been approved by 20 percent of the shareholders, including Arctic Ventures. Without full approval, however, AOL will likely be forced to up the ante. According to analyst Mikael Laséen, a bid by Google would not be a big suprise.

The move by AOL makes sense as it shifts from subscribers as the basis of its revenue model toward one based on advertising.