WASHINGTON (AP) — The nation’s top financial markets regulators say they will look into whether recent stock market turbulence is an indication that current trading practices are not doing enough to protect investors. In a statement issued after a meeting of regulators convened by Treasury Secretary Janet Yellen, the Treasury Department said that regulators believe the core infrastructure of the market has proved to be resilient. But the statement said that the regulators also believed in the importance of completing a study by the Securities and Exchange Commission into what happened in the recent market upheaval that pitted smaller, online investors against massive hedge funds.