Google said it will increase the size of ads that run atop search results, enabling two-line titles and longer descriptions.
Revenue growth accelerated in recent quarters, but analysts expect it to slow in the months ahead.
They re doing this now because they foresee a revenue or profit challenge ahead, said Patrick Moorhead, founder of Moor Insights & Strategy.
Bernstein Research analyst Carlos Kirjner has said Google is squeezing the lemon to extract more money from its search business.
Google executives said they are redesigning the company s ad offerings as users shift to smartphones, which now account for more than half of Google searches.
Marketers generally pay less for each click on an ad on mobile phones, believing they lead to fewer sales.