NEW YORK (TheStreet) -- Shares of 3D Systems (DDD) - Get Report are down roughly 10% after the company priced its 5.95 million share secondary offering at $53.25. 

On CNBC's "Cramer's Stop Trading" segment, TheStreet's Jim Cramer, co-manager of the Action Alerts PLUS portfolio, explained that the share price "did not hold" because of the "gigantic short" positions in the stock. 

In the 3-D printing space, he likes Stratasys (SSYS) - Get Report the most, which has more exposure to the industrial sector. 

"The public is way too long 3D Systems," he concluded, warning investors to be careful with stocks in this industry.

-- Written by Bret Kenwell in Petoskey, Mich.

Follow @BretKenwell

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At the time of publication, Cramer's Action Alerts PLUS had no position in companies mentioned.