An overhaul of listing and trading rules has driven a 16-year-old board for start-ups on the Shenzhen Stock Exchange to an all-time high, and traders believe the listed companies’ above-average earnings growth and exposure to renewable energy will extend the record-setting run.The ChiNext 50 Index of the board’s 50 biggest stocks and the ChiNext Composite Index both broke highs set in 2015 this week, outpacing other equity gauges of yuan-denominated stocks, which have yet to fully recoup their...