Self-described “long-term optimist” Elon Musk made another bold prediction about his car company. That isn’t necessarily good news for Tesla’s stock price—although investors initially appeared enthusiastic.

Ross Gerber, a longtime Tesla shareholder, outlined to BI four reasons he thinks the stock is vulnerable to a 50% pullback this year.

The backlash against the electric vehicle company has intensified as the billionaire ally of President Trump exerts his power over the federal government.