House Speaker Nancy Pelosi on Wednesday said lawmakers should not be barred from trading stock, a practice that has come under scrutiny because it gives members of Congress the opportunity to profit from inside information gained through their official duties. “We are a free-market economy. They should be able to participate in that,” Pelosi, whose venture-capitalist husband holds tens of millions of dollars’ worth of stocks and options, told reporters. Pelosi has long said she has no involvement in or prior knowledge of her husband’s trading decisions. The issue of congressional stock trading has taken on new urgency since the...