Netflix fell as much as 5 percent Wednesday after Citron Research tweeted it was time to short shares of the high-flying video streaming company.
Netflix is the best-performing stock in the S&P 500 this year, up 117 percent. Citron is one of the few research shops whose calls to bet against stocks can move those shares.
"Citron stayed away but finally time to short $NFLX. Comp heating up and doesnt have another trick like $AAPL $GOOG $AMZN. Back to $80" — @CitronResearch
CNBC has received confirmation from Andrew Left, the founder of Citron Research, they have started a short position in Netflix.
Citron Research has been successful with many of its negative calls including several reports on China-based companies.
The firm is most well-known for their report on Longtop Financial Technologies in April 2011, which questioned the veracity of the company's financial statements. Citron was later validated by the market as the shares were delisted and the SEC revoked the company's registration.
Shares of GoPro are down 50 percent since Citron's skeptical report in November of 2014.