Although Facebook’s stock price has slowly crept back over $31, its low point last month of $25.52 (after opening at $38) reflected a declining confidence in Facebook’s ability to monetize. And after General Motors publicly yanked all of its ad spending from Facebook, people really started to talk about whether or not it was even worth it for brands to advertise on the site.

Despite some reports suggesting that Facebook’s mobile revenues are looking up, 33across has some pretty unfortunate news for Facebook today.

According to 33across, advertisers are beginning to focus more on the rest of the web and less on Facebook.

Their “Advertiser and Agency Survey” gauged the climate within a group of 2200 brand marketers and agency execs. What they found was that 71% of those surveyed said that they were focusing 80% of their attention in places not named Facebook. In March, the same survey showed that only 58% of the marketers were putting their eggs far away from the Facebook basket.

In March, an albeit small but present 4% said they were putting 80% of their effort in Facebook advertising. Now, that number has dropped to 0%. Only 7% of respondents are putting the majority of their bucks into Facebook ads.

“What was particularly surprising to me was the dramatic shift in advertiser and agency attitudes towards Facebook after the IPO,” said Allie Kline, CMO of 33Across. “Facebook’s future greatly depends on advertiser spend – on both the web and mobile devices – and this survey indicates that they have some work to do to restore advertiser confidence in their Facebook investments.”

But when asked about future spending, opinions have changed drastically since Facebook’s IPO. More than five times the number of respondents pre-IPO now say that they were planning on “decreasing their Facebook spend.”

It looks to be all about confidence. Facebook has to prove to these marketers that the network is still worth their time. Getting GM to come back to the table would be a huge score for Facebook, as a major U.S. brand would be seen as feeling comfortable placing millions of their dollars into Facebook.