Analyst Update: 21Vianet Group Inc, OSI Systems, Inc., and Vipshop Holdings Ltd

Analysts are weighing in on data center services provider 21Vianet Group Inc (NASDAQ:VNET), electric components specialist OSI Systems, Inc. (NASDAQ:OSIS), and e-tail stock Vipshop Holdings Ltd - ADR (NYSE:VIPS). Here's a quick roundup of today's brokerage notes on VNET, OSIS, and VIPS.

• VNET reported better-than-expected earnings last night, but a "very weak" full-year revenue forecast prompted JPMorgan Securities to lower its rating to "underweight" from "neutral." As such, the stock is down 12.4% at $9.21, and has landed on the short-sale restricted list. Year-to-date, 21Vianet Group Inc has now surrendered over 56% of its value. This should come as music to the ears of short sellers, who have been upping the bearish ante of late. During the last two reporting periods, short interest on VNET rocketed 40.6%, and now accounts for over 11% of the stock's float.

• On the other hand, an earnings beat has OSIS 11.5% higher at $67.64 -- its largest one-day percentage gain in over three years. In fact, the stock is currently on track for its first close north of the 200-day moving average since late January. Fueling the fire, Benchmark and B. Riley raised their respective price targets on OSI Systems, Inc. to $70 and $66.50. This simply echoes the bullish stance analysts have maintained toward the shares. Specifically, all four brokerage firms tracking OSIS have handed out a "strong buy" endorsement.

• Lastly, VIPS is off 0.4% at $16.01 following a mixed round of analyst attention. On the bright side, BofA-Merrill Lynch lifted its assessment to "buy" from "neutral," and was one of four brokerage firms to upwardly revise its price target. However, despite raising its target price, Deutsche Bank also slashed its outlook to "hold" from "buy." Technically speaking, Vipshop Holdings Ltd hasn't disappointed, rallying hard off its late-May lows near $10. Yet, short interest still accounts for nearly 11% of the stock's float, or 6.4 sessions' worth of trading activity, at VIPS' usual daily volumes.