In case there is still any confusion on whose behalf the US regulators work when they "fine" banks, the latest announcement from Finra should make it all clear. Recall the spectacle full of pomp and circumstance surrounding NY AG Scheinderman's demolition of Barclays after it was announced that the bank had lied to its customers to drive more traffic to Barclays LX, its dark pool, and allow HFT algos to frontrun buyside traffic. Yes, it was warranted, and the immediate result was the complete collapse in all buyside Barclays dark pool volume, meaning predatory HFT algos would have to find some other dark pool where to frontrun order flow. Such as Goldman's Sigma X. Which brings us to, well, Goldman's Sigma X, which moments ago, in a far less pompous presentation, was fined - not by the AG, not by the SEC, but by lowly Finra - for "Failing to Prevent Trade-Throughs in its Alternative Trading System." The impact: "In connection with the approximately 395,000 trade-throughs, Goldman Sachs returned $1.67 million to disadvantaged customers." The punchline, or rather, the "fine": $800,000.