had a short order pegged to the offer in a major ETF today. thick book, penny spread. as soon as the order went out, it not only crossed other mkts books, but their own and removed liquidity from their own book... 30 cents (1%) lower !!!! had my desk call them up and their reply was "it was a good fill, pegged orders don't always work, our customers are aware of this, use at your own risk." so for those that don't know, arca is offering a broken routing feature that doesn't work and that violates regnms regularly... if you want anything resembling a decent fill, don't use it.