Sina Corp (SINA) is down $1 to $29.31 and investors are buying puts on the Chinese Intenet company Tuesday. Pacific Crest analysts downgraded SINA yesterday, saying Street estimates for 2009 and 2010 earnings are too high! They believe the company will struggle to maintain market share and Focus Media (FMCN) deal adds uncertainty. Sentiment in the options market is clearly defensive Tuesday, with 12,000 puts and only 325 calls traded (chart). Buyers of Sept 17.5 puts leading the activity and looking for a move below $17.50, or 40 percent, by the September expiration.