The whole point of Levine's article is that HFTs did not offer the dark pool operators "boat loads of money". The dark pool operators gave the HFTs sweetheart deals to induce them to trade in their pools. They didn't do that because the HFTs paid them. They did it because without the automated traders, the dark pools wouldn't have worked at all.
By the numbers, if the big institutional investors wanted HFTs out of the dark pools, Barclays should have kicked them to the curve. Not ethically, but simply from a practical business perspective. But Barclays couldn't do that... or, they could, but then the institutional clients would have stopped trading in the LX pool, because they'd never get filled.
The whole point of Levine's article is that HFTs did not offer the dark pool operators "boat loads of money". The dark pool operators gave the HFTs sweetheart deals to induce them to trade in their pools. They didn't do that because the HFTs paid them. They did it because without the automated traders, the dark pools wouldn't have worked at all.
By the numbers, if the big institutional investors wanted HFTs out of the dark pools, Barclays should have kicked them to the curve. Not ethically, but simply from a practical business perspective. But Barclays couldn't do that... or, they could, but then the institutional clients would have stopped trading in the LX pool, because they'd never get filled.