The company also reported its slowest revenue growth in 18 quarters in the three months ended June 30, and said Chairman Max Levchin would step down “to pursue other interests.” There has been no decision on a replacement, Yelp said. Yelp, whose shares fell more than 16 percent in extended trading, said it expected to report net revenue of $139 million-$142 million in the third quarter – well below the $152.6 million average analyst estimate. Yelp’s subscriber growth has been slowing in a crowded market.