joining us for his facebook forecast is senior internet analyst john blackledge.he company sets expectations for itself. do they run the risk of getting ahead of themselves? >> i don't think so. we are looking for 57% ad revenue growth driven by mobile. remember the company has beaten the last two quarters and we think they can beat again driven by upside to revenue and earnings. that would lead numbers to go up and we think the stock will grind up. >> there were some comments that maybe the real estate for their advertising was getting a little full. how much inventory do they have to work with and how much slack can instagram pick up from facebook? >> great question. so cfo mentioned that the ad load growth contribution would begin to slow down in second half '17. that is a ways out. that will not impact this quarter or next quarter. back half of next year. your report on instagram helping, there are levers for facebook's ad revenue growth. instagram is one of them. they rolled out the instagram stories in mid august. the company as of a couple of weeks ago said