Facebook underwriters holding the price with green shoe

http://en.wikipedia.org/wiki/Greenshoe#Risk_to_Investors

  The SEC currently does not require that underwriters publicly report
  their short positions nor short-covering transactions. Investors who
  are unwary of underwriter stabilizing activity who choose to invest in
  what they perceive to be a stable issue can encounter volatility
  when the underwriters pause or complete any stabilizing activity.
  "Cast in the most negative light, price stabilization might be seen
  as a means of transferring risk to a relatively naïve segment of
  the investor population."

How is this allowed by the SEC?