Notice of Designation of a Longer Period for Commission Action on Proceedings To Determine Whether To Approve or Disapprove a Proposed Rule Change, as Modified by Amendment No. 1, To Amend Its Rules Regarding the Minimum Increments for Electronic Bids and Offers and Exercise Prices of Certain FLEX Options and Clarify in the Rules How the System Ranks FLEX Option Bids and Offers for Allocation Purposes