The head of short selling firm Hindenburg Research wasted little time trolling Elon Musk on Twitter after the billionaire put his deal for the social media company on hold.

“I’m looking on the bright side of life this morning,” Hindenburg founder Nathan Anderson wrote just over a half hour after Musk announced he was pausing his pursuit of Twitter, pending details on how many accounts on the platform are fake.

Hindenburg announced early this week it was betting Twitter shares would fall, citing its belief there was significant risk Musk would cut the $54.20-a-share price he’s offered to pay.

Musk, who is famously not a fan of short sellers, responded to the firm’s thesis in a May 9 tweet: “Interesting. Don’t forget to look on the bright side of life sometimes!”