Analysts are weighing in today on snack-food firm Diamond Foods, Inc. (DMND - 36.42), communications equipment concern Ciena Corporation (CIEN - 13.74), natural gas giant Chesapeake Energy Corporation (CHK - 25.29), alternative energy issue JinkoSolar Holding Co., Ltd. (JKS - 6.48), and semiconductor stock OmniVision Technologies, Inc. (OVTI - 12.83). Here's a quick roundup of today's upgrades and downgrades of note.

• Amid its ongoing walnut accounting scandal, DMND today was hit with a steep price-target cut to $46 from $94 at Jefferies. However, the stock is up 3.7% at last check, erasing a portion of its 33.9% year-to-date deficit. With DMND's Relative Strength Index (RSI) docked at an anemic 19, it's quite likely that today's advance is simply an oversold bounce, as opposed to a meaningful rebound.
• Meanwhile, CIEN is down 1.9% after Barclays lowered its price target to $19 from $20. The downwardly revised target implies expected upside of 35.6% to Monday's close at $14.01. More recently, however, CIEN has found a ceiling in the $14-$15 neighborhood, which has served as a technical ceiling since early August. In fact, shorts are overwhelmingly betting on CIEN to slump, with short interest accounting for nearly 28% of the equity's float.
• Capital One downgraded CHK to "add" from "strong buy," sparking a 1.5% decline in the stock at last check. The shares are now trading south of their year-to-date breakeven, located near the $26 level. On the other hand, the $24 area could provide a cushion for CHK, as this region previously served as staunch resistance during the bulk of 2010.
• After slashing its shipment and revenue guidance on Monday, JKS was hit with a price-target cut to $7 from $8 at Deutsche Bank. The stock is off 4% this morning, adding to yesterday's drastic 13% drop. Most analysts are already a little leery of JKS, with Zacks reporting that only one brokerage firm out of six has deemed the stock worthy of a "buy" rating. However, with four "holds" out there, the technical laggard could still be vulnerable to downgrades going forward.
• Finally, OVTI is off 2.4% in the wake of a downgrade to "hold" from "strong buy" at Needham. Earlier in the session, the shares tumbled to a new annual low of $12.52. The stock has been trending steadily lower since May, and OVTI's downward momentum accelerated after the firm issued a second-quarter revenue warning earlier this month. Now, the security is sitting on a substantial year-to-date drop of 55.6%, woefully underperforming the broader equities market.