Wall Street's concerns on Snap Inc.'s (SNAP) - Get Report business prospects has walloped the wallets of the social media upstart's co-founders.

With Snap shares down a startling 39% since its March initial public offering (IPO), the combined net worth of Evan Spiegel and Robert Murphy have plunged some $4.3 billion, according to Bloomberg data. The two Snap founders each have a net wealth of $3.3 billion, per Bloomberg data.

Judging by Wall Street's assessments on Snap of late, each billionaire may be at risk of losing more wealth before the year is out.

Cowen analyst John Blackledge recently slashed his rating on the company to "market perform" from "outperform." Blackledge said ad revenue through 2022 will suffer as Snap faces competition within digital advertising. He added that monetization efforts are "taking longer to play out."

The move by Cowen follows in the footsteps of fellow Snap underwriter Morgan Stanley, which last week cut its rating to "equal weight" from "overweight" with a price target of $16.

Snap's shares fell 1.1% to $14.97 on Wednesday morning.

More of What's Trending on TheStreet: