Here are 10 reasons why  Federal Reserve chairman Ben Bernanke will announce that the central bank intends to do more than merely lengthen its balance sheet maturities, a move known as Operation Twist.

The reasons are from a client note by David A. Rosenberg, chief economist and strategist for Gluskin Sheff + Associates Inc.

1. Just go back to Aug. 9. The Fed was supposed to make a more emphatic comment in the press statement about extended period as it pertained to the length of time the Fed would stay ultra-accommodative on the rates front. Bernanke went much further than anyone thought with his pledge to keep the funds rate at the floor at least to mid-2013.

2. [Fed Chairman] Ben Bernanke has shown repeatedly that he is willing to take risks and be very aggressive.

3. Everyone knows that the Dow finished the Aug. 9 session with a huge 430 point gain after the FOMC [Federal Open Market Committee] press statement was fully digested. Not only that, but when Bernanke held his two-day meeting in mid-December of 2008 and unveiled QE1 [round no. 1 of quantitative easing], the Dow soared 360 points. And last November, the day after that two-day meeting when Bernanke made it clear in his Washington Post op-ed article how key it was to ignite the stock market, the Dow jumped 220 points. It may all be just for a near-term trade, but in an industry where every basis point counts, who wants to be short knowing all that?

4. At that August meeting, we know both from the statement and minutes that additional rounds of unconventional easing were discussed. And Mr. Bernanke made it very clear at Jackson Hole that they would be on the table again at the coming meeting.

5. The Fed would like to be out of the picture during the election campaign (especially if [Gov.] Richard Perry ends up winning the GOP nomination).

6. The Fed has cut its GDP forecasts at each of the past three meetings.

7. The stock market is actually little changed from where it was at the last meeting and we know based on that Washington Post op-ed, that it is equity valuation (specifically the Russell 2000) that Ben wants to see rally. Sanctioning lower bond yields is just a means to that end.

8. There is no fiscal stimulus to bolster the economy, with the odds are very high that the Obama jobs plan ... will be dead-on-arrival on the House floor. The Fed is the only game in town.

9. Financial conditions have tightened nearly 100 basis points since the spring and deserve a policy response.

10. Bernanke announced at Jackson Hole that this coming meeting was going to be a two-day affair, not one day. The last time he did this was back in December 2008 and that was when he invoked QE1. There has to be a reason why it is two days, and it must be because he wants to build the case for three dissenters. The Board is being sequestered for a reason!

Finally, Rosenberg points out in his note that Bernanke, in a Oct. 2, 2003, speech, said surprising the markets with monetary policy changes is essential to measuring the effect of those policy changes.

If Bernanke wants to juice the stock market, then he must do something to surprise the market. 'Operation Twist' is already baked in, which means he has to do that and a alot more to generate the positive surprise he clearly desires. If seems that Bernanke, if he wants the market to rally, is going to have to come out with a surprise today, Rosenberg wrote.

If he doesn't, then expect a big selloff.