China freezes more than 40 IPOs pending an investigation as regulatory screws tighten The securities regulator also indicated it would pursue cooperation with the US on auditing supervision. – Two Chinese stock exchanges have frozen more than 40 planned IPOs, according to Reuters. – The exchanges say the freeze is due to a pending investigation by China's securities regulator. – The securities regulator also indicated it would pursue cooperation with the US on auditing supervision. – [Sign up here for our daily newsletter, 10 Things Before the Opening Bell] . Two Chinese stock exchanges have frozen more than 40 planned…