As the one-year anniversary of the flash crash approaches, Securities and Exchange Commission Chairman Mary Schapiro spoke to reporters about the event on the sidelines of a Senate appropriations hearing.

Last year's unprecedented drop sent the Dow Jones Industrial Average down some 700 points in minutes before it sharply rebounded — a rapid breakdown that exposed deep flaws in the mostly electronic U.S. marketplace.

Schapiro said the agency has moved swiftly to implement key reforms, including circuit breakers to dampen stock market volatility; new rules for breaking clearly erroneous trades; rules banning "naked access" to the market; and a prohibition on stub quotes, or offers to buy or sell stock at prices that are not in line with the prevailing market.

Now, the SEC is preparing to seek comments on its limit up-limit down proposal, a plan seen as more sophisticated than disruptive circuit breakers because it would restrict traders to price bands without halting trading outright.

"Can I guarantee we will never have another flash crash? No," Schapiro said. "But I think these are really important steps to take that I think go a really long way toward fortifying our market structure."

Despite these key steps by the SEC, Schapiro said a lot more still needs to be done.

Schapiro said that in the next few months, she hopes the SEC will "have enough breathing room" to finalize rules on a consolidated audit trail and large trader reporting. These two rules are designed to help the SEC better track trading across the fragmented U.S. equity markets — an issue that proved difficult for the agency when it began the task of reconstructing what went wrong on May 6, 2010.

"I think we have learned a lot in the process, but we have more to do and we are very, very focused on getting those things done even though the Dodd-Frank effort is taking up a lot of our bandwidth right now," Schapiro said.

The sweeping U.S. Dodd-Frank legislation requires the SEC to write nearly 100 new rules for Wall Street by this summer.

Also still being explored are all the various recommendations laid out for the SEC and Commodity Futures Trading Commission in a flash crash report earlier this year written by a joint advisory committee.

The many recommendations in that report include imposing fees on high-speed traders to curb large numbers of order cancellations, market maker obligations for high-frequency traders and a rule that would clamp down on anonymous trading.

When asked about proposals such as market maker obligations, Schapiro said these issues are "all still very much on the table.

"We want to understand how these potential actions ... fit together," she added.

CFTC Chairman Gary Gensler, meanwhile, said his agency is still working with the SEC toward implementing cross-market circuit breakers.

In addition, he said, proposed rules in the works at the CFTC for exchanges and swap trading platforms would require pre-trade risk filters and the agency also continues to work on "a testing and supervision" rule as well.