By virtue of a new agreement between Yahoo and Google, search results from the two rivals may start looking even more alike.

Yahoo has signed an agreement with Google under which, "Google will provide Yahoo with search advertisements ..., web algorithmic search services..., and image search services."

So now, Yahoo will draw some if its web search results, image results, and attendant advertising from Google.

This is nothing new; Yahoo has already been displaying search results provided by Microsoft's Bing since an agreement between those two rivals in 2009. The Yahoo/Microsoft agreement is scheduled to run through 2019. This new Yahoo/Google agreement does not preclude Yahoo from drawing some search results (and advertising) from Microsoft's services.

"Under the Services Agreement, Yahoo has discretion to select which search queries to send to Google and is not obligated to send any minimum number of search queries. The Services Agreement is non-exclusive and expressly permits Yahoo to use any other search advertising services, including its own service, the services of Microsoft Corporation or other third parties."

Details of the Yahoo/Google deal were included in an 8-K filing by Google on October 20. (Public companies are required to file an 8-K with the SEC to reveal information [such as big deals] that would be important for investors to know about.)

According to the the SEC filing, the Yahoo/Google agreement went into effect on October 1, 2015 and is scheduled to run through the end of 2018.