Chinese broker Sinolink Securities has raised its margin deposit ratio for new financing contracts to 100% from 80%the first Chinese broker to tighten requirements during the market rallyThe move reflects concern over the sustainability of the surge, as mutual funds also curb new orders after big gains. Chinese stocks have added over $1 trillion in value in the past month, with the Shanghai Composite at a 10-year high and the CSI 300 up more than 20%, though weak economic data is tempering optimism. This article was written by Eamonn Sheridan at investinglive.com.