It's no secret that the SEC is taking a look at high-frequency trading and other modern innovations. It's already indicated it will ban flash orders and it seems skeptical of the worth of IOIs. What appears to be happening is a wide-ranging review of the entire trading infrastructure, end-to-end.

Traders notes the SEC's Strategic Plan for 2010 to 2015 indicates the agency will be looking at the pillars of the modern market, Regulation NMS and ATS. Both have been critical to the cost and trading structure of the market, and both resulted in many millions of dollars invested in technology to support these structures. And now they are up for review. Any changes are likely to come this fall in the form of specific rules, notes Traders. How groundbreaking will all this be? There will likely be some moves aimed at enhancing price efficiency, allowing more access to dark pool-like services, and supporting the NBBO process.

The SEC also noted that one of its initiatives may be "strengthening the incentives for investors to display trading interest, and thereby contribute to the public price discovery process." Again, the SEC did not elaborate, but efforts to strengthen these incentives could involve alterations to the trade-through rule in Reg NMS. There's a lot of support for the idea that the rise of dark pools and the like have increased market efficiency. But you could mount an argument that small investors do no benefit. There will be a lot to discuss. It will get pretty technical but these are critical issues. 

For more:
- here's the Traders article

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