BY JACOB BUNGE

New measures aimed at curbing the short selling of U.S.-listed stocks had little impact in slowing downward momentum during often-turbulent trading sessions over the past week.

The rules introduced in February saw exchange operators enact a temporary shield when a stock loses more than 10% of its value in a single session. Shorting is then permitted only if the sale price is above the current highest bid nationally. The restriction lasts for the rest of the …