The trick to successful investing is knowing when to take profits and walk away. In this case, Cramer says it's time.
That is, "If you own Onyx Pharmaceuticals based on my recommendation from April, you now have a 50% gain. It's time to ring the register. Take some profits," Cramer said.
Shares of Onyx shot higher on Monday after the company's board rejected a $120 share takeover offer from Amgen, saying the offer significantly undervalued the drug company. It represented a 38% premium.
However, Onyx also said it would consider a sale of the company
"Immediately analysts started coming out of the woodwork," Cramer explained. "Lazard said Onyx could be taken out at $130 to $140, Deutsche Bank said $140, Bernstein said $180."
That's a game that Cramer doesn't want to play.
"While it's possible Onyx will catch a higher bid, I also think that the easy money has already been made here. Don't be greedy."