Goldman Sachs downgraded the stock to "neutral" and set a $28 price target, as the company has limited visibility.
Credit Suisse downgraded Thoratec to "neutral" from "outperform" and set a $27 price target, as the company lowered its guidance meaningfully.
The stock was down 26.13% to $24.06 in pre-market trading on Thursday.
Separately, TheStreet Ratings team rates THORATEC CORP as a "buy" with a ratings score of B-. TheStreet Ratings Team has this to say about their recommendation:
"We rate THORATEC CORP (THOR) a BUY. This is driven by some important positives, which we believe should have a greater impact than any weaknesses, and should give investors a better performance opportunity than most stocks we cover. The company's strengths can be seen in multiple areas, such as its increase in net income, revenue growth, largely solid financial position with reasonable debt levels by most measures, reasonable valuation levels and good cash flow from operations. We feel these strengths outweigh the fact that the company has had lackluster performance in the stock itself."
You can view the full analysis from the report here: THOR Ratings Report