SIFMA provides comments to the Securities and Exchange Commission (SEC) regarding several issues addressed during the SEC’s Market Structure Roundtable. The issues include, (1) preventing price gaps and erroneous trades; (2) market-wide circuit breakers; (3) market center obligations; (4) market maker obligations; (5) high frequency trading, high speed trading and related issue; (6) internalization and undisplayed liquidity; (7) trade-at rule; (8) access fees and sub-penny quoting; (9) market data; (10) risk management – market access; (11) regulatory consistency; (12) consolidated audit trail and large trader reporting; and (13) rules 605 and 606: market quality and order routing data.