(AP) -- Yahoo, AOL and Microsoft are joining up to sell each other's advertising inventory, according to published reports.
Citing unnamed sources, the blog AllThingsD reported earlier Wednesday that executives from Yahoo Inc., AOL Inc. and Microsoft Corp. told Web publishers and ad buyers about the plan at a presentation on Tuesday.
Yahoo and AOL declined to confirm the report. A Microsoft representative did not immediately respond to messages for comment.
A deal could help the companies slow the fast growth of Google and Facebook in the lucrative online display advertising market.
In a statement, Yahoo says it has "longstanding relationships" with AOL and Microsoft and will continue to work with them in years to come. AOL says it continues to look to expand its relationships with publishers, including Yahoo and Microsoft.
Explore further: Facegloria: Facebook for Brazil's Evangelicals