Taiwan Stock Exchange and Taipei Exchange will place four stocks under trading restrictions for five sessions from Aug. 24 through Aug. 28, citing elevated valuations, concentrated trading and sharp price gains. Visual Photonics Epitaxy (2455.TW), Usun Technology (3498.TW), Myson Century (5314.TW) and United Recommend International (5321.TW) will use manual order matching at two-minute intervals. Visual Photonics Epitaxy had a price-to-earnings ratio of 99.51x, a price-to-book ratio of 20.56x and a daily turnover rate of 7.55% on Aug. 21, while one investor accounted for more than 10% of its daily trading value, exceeding NT$100 million. Usun Technology gained 30.24% over six trading sessions, Myson Century rose 59.43% over six sessions and United Recommend International jumped 203.75% across the latest 90-session period. The exchanges also placed 45 stocks on watch lists, including 15 on the Taiwan Stock Exchange list and 30 on the Taipei Exchange list.