HONG KONG, March 21 (Reuters) - Hong Kong shares erased Thursday's early gains, slipping to their fourth loss in five days with Chinese internet giant Tencent Holdings a top index drag on a number of brokerage downgrades despite matching earnings estimates.
The Hang Seng Index closed down 0.1 percent at 22,225.9. The China Enterprises Index of the top Chinese listings in Hong Kong shed 0.3 percent.
The CSI300 of the leading Shanghai and Shenzhen listings closed up 0.2 percent at 2,615 points. The Shanghai Composite Index gained 0.3 percent.
* Tencent Holdings finished off intra-day lows, but down 4 percent at its lowest close since Dec. 31, hurt by downgrades from Deutsche Bank and CLSA despite posting 2012 earnings late on Wednesday that were in line with expectations. DB analysts downgraded Tencent from "buy" to "hold" while trimming its target price by 8 percent, citing near-term margin pressures from mobile and e-commerce initiatives that would bear fruit in the longer term.
* China's HSBC flash PMI came in at a higher-than-expected 51.7 in March from 50.4 in February, triggering a brief reversal of index losses in mid-morning trade. However, the gains later faded.
* A flurry of companies are due to post corporate earnings after markets close for the day, including Li & Fung, China Unicom and Petrochina.