Industry groups are taking seriously new legislation introduced on Capitol Hill that would impose a tax on all securities trading activity, even if most observers see little likelihood of such “Robin Hood” tax legislation being enacted by a polarized Congress. Sen. Tom Harkin, D-IA, and Rep. Peter DeFazio, D-OR, last week introduced the Wall Street Trading and Speculators Tax Act, which would impose a 3 basis point tax on all non-consumer trading of securities, stocks, bonds, interests in partnerships and trusts, and derivative financial instruments. The tax would not be applied on new issuance or debt with...