Humm, réponse quasi valide mais pas exacte
La réaction haussière brutale est apparue minutes après la publication du Tresor US du communiqué suivant :

(en bref, ce n’est pas un robinet supplémentaire de liquidité que Ben vient d’ouvrir, mais une vanne de barrage hydraulique par ses copains du Trésor)

• Treasury Announces Supplementary Financing Program Washington-
• The Federal Reserve has announced a series of lending and liquidity initiatives during the past several quarters intended to address heightened liquidity pressures in the financial market, including enhancing its liquidity facilities this week. To manage the balance sheet impact of these efforts, the Federal Reserve has taken a number of actions, including redeeming and selling securities from the System Open Market Account portfolio.
• The Treasury Department announced today the initiation of a temporary Supplementary Financing Program at the request of the Federal Reserve. The program will consist of a series of Treasury bills, apart from Treasury’s current borrowing program, which will provide cash for use in the Federal Reserve initiatives.
• Announcements of and participation in auctions conducted under the Supplementary Financing Program will be governed by existing Treasury auction rules. Treasury will provide as much advance notification as possible regarding the timing, size, and maturity of any bills auctioned for Supplementary Financing Program purposes.