(Click for video linked to a searchable transcript of this Mad Money segment)

Cramer had advocated long positions in these stocks for quite some time. But no more.

"After having some incredible runs this year, I think it's time to ring the register on pretty much any biotech that's smaller than $10 billion," Cramer said.

That includes but is not limited to up 459% for the year, Acadia Pharma up 390%, Celldex up 323% ytd, NPS Pharma, up 263%, Isis Pharma up 219% and Tesaro up 124%.

"The same goes for all of the other small-cap biotechs that are up huge for the year," Cramer said.

Considering the gains, Cramer thinks it would be irresponsible not to take at least some money off the table. In this sector, he feels it's especially prudent given smaller biotechs are often nothing more than bets on FDA approval.

That was the case with Ariad, said Cramer. "Earlier this week, the FDA halted enrollment in clinical trials of Ariad's main drug candidate because it seemed to be causing blood clots. As a result, Ariad lost 66% of its value in a single day."

Now that's not to say Cramer thinks something similar will happen with the stocks listed above – he doesn't. It's not to say he's bearish on the group – he's not.

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It's simply that biotechs under $10 billion tend to be binary bets on FDA approval. And considering the ytd gains, he thinks it's time to take profits and call it a day.

"I still adore these small-cap biotech companies," Cramer added," but I hate greed, and if you don't ring the register on their stocks here, you are being a bad little piggy."

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