The class B stock, which often sees volume of less than 10,000 shares in a day, had already changed hands about 600,000 times as of noon ET, according to FactSet. Meanwhile, the class A shares were flat on a more modest rise in volume, and its non-voting class C shares fell 0.3%.
Shares of Discovery have fallen sharply over the past week as Archegos Capital Management was forced to liquidate its position in the communications company and several other names. Those sell-offs hit both share classes of Discovery in a similar manner, however, unlike the moves on Wednesday.
Discovery declined to comment.
The class B shares account for 10 votes per share versus one vote per share for class A, according to Discovery's investor relations website. Roughly 95% of the class B shares are held by media executive John Malone, according to FactSet.
-CNBC's Chris Hayes contributed to this report.