Herbalife shares tumbled Tuesday after an analyst at SunTrust Robinson Humphrey downgraded the company from a “buy” to a “neutral” rating, and lowered his 12-month target price from $75 to $55.

Shares fell $11.62, or 21 percent, in Tuesday trading to close $44.26. Herbalife shares traded for more than $80 a share as recently as January.

The downgrade came a day after the Los Angeles nutritional supplement company reported sharply lower quarterly profits that fell well short of analysts’ expectations. Herbalife reported that its profit in the quarter ended Sept. 30 dropped more than 90 percent compared to the same period last year, due to changes in the value of Venezuelan currency and declining sales in the Americas.

It’s the latest headache in a persistent stream of bad news for Herbalife, which has been under attack for nearly two years by Pershing Square Capital Management’s Bill Ackman, who says the company’s business model is a pyramid scheme.

Herbalife has repeatedly denied the allegations, but the U.S. Federal Trade Commission is investigating the company’s practices, and the company recently paid $15 million to settle a class action lawsuit filed by a former distributor who echoed Ackman’s accusations.