For regulators hoping to rein in wild moves in small stocks like the 17-fold surge in GameStop Corp. last month, India has a system worth studying. Rules created by the Securities and Exchange Board of India together with the nation’s exchanges are aimed at preventing unwarranted price swings and manipulation of stocks with a market capitalization below Rs 25,000 crore ($3.4 million). The so-called graded surveillance measure (GSM), which was introduced in 2017, is unique and helps prevent GameStop-like surges in small caps, according to Bhargavi Zaveri, a researcher at the Mumbai-based Finance Research Group. “The measure targets firms whose returns are believed to be out of sync with their fundamentals, and puts them under a level of scrutiny that stops everyone from trading in it,” Zaveri, who co-authored a paper on the mechanism, said in an interview. “We tracked practices by regulators in 30 jurisdictions around the world and didn’t find anything that linked surveillance to the fundamentals of the firm.”