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Short interest in the two-week period ending April 15 fell for three of the four 3D printing stocks we follow. The most recent period followed the trend set in the two prior periods, with short interest declining in these stocks as share prices have risen. For the two-week settlement period to April 15, for example, shares in these companies rose in a range of 9% to nearly 18%.

Then, on Friday, one of the 3D printer makers chopped guidance and that may have put an end to the rising stock prices. The first earnings report from one of these firms is due next week, and all will have reported by the middle of May. The next couple of weeks should be interesting.

Short interest in 3D Systems Corp. (NYSE: DDD) fell 5.6% to 36.36 million shares. Some 34.5% of the company’s float is short. Days to cover fell to 20.6. In the two-week short interest period, the share price rose about 18%. The stock’s 52-week range is $26.29 to $69.56, and shares closed at $27.23 on Friday. The company lowered its first-quarter guidance last Friday and said it would update full-year guidance when it reports results on May 6. The share price fell nearly 10% on Friday.

Stratasys Ltd. (NASDAQ: SSYS) saw short interest rise by 6.6% in the first two weeks of April to about 10.64 million shares, or about 23.8% of the company’s float. Days to cover rose to 10.9. The share price rose about 14.5% in the two-week period. The stock closed at $51.28 on Friday, down about 6% on the day, and the 52-week range is $50.70 to $130.83. The low was posted Friday as Stratasys got caught in the wake of 3D Systems’ guidance cut.

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Short interest in ExOne Co. (NASDAQ: XONE) fell 3.6% to 3.39 million shares. About 37.3% of the company’s shares are now short. Shares of ExOne fell rose nearly 16% in the two-week period. The stock’s 52-week range is $13.19 to $48.66, and shares closed at $14.61 on Friday, down 2.6% for the day. Days to cover rose to nearly 19.

Voxeljet A.G. (NYSE: VJET) saw short interest fall 5% to 1.89 million shares, with days to cover rising to 12.6. The share price rose more than 9% in the two weeks to April 15. The stock closed at $8.71 on Friday night, down about 1.3%, in a 52-week range of $7.13 to $27.41.