SIFMA provides comments to the Securities and Exchange Commission (SEC) requesting an extension of the implementation date for the plan (Limit Up-Limit Down) to address extraordinary market volatility submitted to the SEC as required by Rule 608 of Regulation NMS under the Securities Exchange Act of 1934 (Exchange Act), File No. 4-631.  SIFMA is extremely concerned that there is not enough information available to SIFMA members and industry participants to properly develop the technology specifications for the necessary systems and coding changes.  SIFMA believes that proceeding with the current implementation schedule would create a great deal of risk, as well as a situation in which firms are required to implement significant systems and coding changes without sufficient time to conduct testing.