The turnover at the top of the Securities and ExchangeCommission comes as the agency copes with challenges ranging fromhigh-frequency trading and the regulation of the money marketindustry to the writing of many of the rules required by theDodd-Frank Act. A Reuters story notes that another challenge is figuring out whowill run the SEC over the long run. President Obama named SECCommissioner Elisse Walter to replace the outgoing chairman, MarySchapiro, but is expected to nominate a permanent successor beforeWalter's term expires at the end of 2013. While Walter serves aschair, the commission will have two GOP voters and two Democraticvoters, a split that could make it harder to pass key measures,Reuters notes.

The Wall Street Journal argues that Schapiro's departureleaves a “regulatory void” and that major issues like the Volckerrule may have to wait until a permanent chairman is in place.Possible nominees include Mary John Miller of the Treasury, SallieKrawcheck, formerly of Bank of America, and Finra Chairman RobertKetchum. And it suggests that some key SEC officials appointed bySchapiro may exit in her wake, including enforcement chief RobertKhuzami.

MarketWatch offers Walter a to-do list, suggesting that she use more sophisticated methodsto monitor computerized trading, coordinate better with theCommodity Futures Trading Commission, support Robert Khuzami andthe enforcement team, and try to slow the revolving door betweenthe SEC and securities firms.

See the Reuters story here, the Journal story here, and the Marketwatch story here. For earlier coverage, see SEC Chairman Schapiro To Step Downand SchapiroNears Exit With Mission Unfinished.