Bill Ackman's bullish call on this stock sent shares up 6%

Legendary hedge fund activist investor Bill Ackman has made a lot of short calls. But his long pick late in the day at the Sohn Conference Foundation in New York sent one company's stock spiking.

Jarden Corp. shares shot up more than 6% in after-hours trading after the stock was one of two that Ackman threw his considerable weight behind.

Ackman lauded Jarden Corp., whose CEO he has before paired with, for having "superior" operations and went as far as to hold the stock up next to other platform companies like Liberty Media and InBev-Anheuser Busch.

Ackman called CEO Martin Franklin "incredible" and praised him for building a company that is "perpetually undervalued."

The market clearly got bullish on Ackman's sentiment: the stock was up more than five percent just moments after Ackman's call.

He also reiterated his support for Valeant Pharmaceuticals. He first invested in the pharmaceuticals company in March.