Senator Elizabeth Warren is calling on regional Federal Reserve Banks to set rules that would prevent their leaders from trading individual stocks, following recent disclosures that the chiefs of the Boston and Dallas banks actively traded stocks and other investments last year.

“The controversy over asset trading by high-level Fed personnel highlights why it is necessary to ban ownership and trading of individual stocks by senior officials who are supposed to serve the public interest,” Warren wrote in letters addressed to the leaders of the 12 regional Fed banks.