** Shares of social media firms rise premarket after Google parent and YouTube-owner Alphabet GOOGL.O beat Q1 ad sales estimates
** Instagram-parent Meta Platforms META.O up 4.3%, image-sharing platform Pinterest PINS.N up 4.5% and Snapchat-owner Snap SNAP.N rises 2.5%
** Revenue from Google's ad business, which makes up nearly three-quarters of its overall revenue, rose 8.5% to $66.89 billion in the quarter, above analysts' estimates of 7.7% rise
** GOOGL said its AI investments were powering returns at its ad business
** SNAP, META set to report results next Tuesday and Wednesday, respectively, while PINS is expected to post earnings on May 9 - LSEG data
** YTD, PINS down 11.2%, SNAP down 22.7%, META down 8.9%, while Alphabet is down 15.9%
(Reporting by Medha Singh)
((medha.singh@thomsonreuters.com))