The Fed's independence doesn't mean isolation. A functional working relationship with the Treasury is crucial for practical matters like ensuring Treasury market liquidity and coordinating bank regulation, areas where responsibilities overlap.

The Fed's intervention in funding markets, while not officially labeled Quantitative Easing, directly helps the Treasury finance its debt, effectively monetizing it and providing critical liquidity to markets.

While shrinking the Fed's balance sheet is effectively off the table, a significant internal debate focuses on its composition. The key question is whether the Fed should hold assets proportional to Treasury issuance or shift to mostly short-term bills to insulate its profits from political scrutiny.

The Treasury actively stimulates liquidity by altering its debt issuance strategy. By issuing more short-term T-bills (bought by banks) and fewer long-term bonds, it effectively monetizes fiscal spending. This 'Treasury QE' is a major, under-the-radar source of liquidity for markets.

The Fed's plan to reinvest maturing mortgage-backed securities (MBS) into Treasury bills is a stealth liquidity injection. The US Treasury can amplify this effect by shifting issuance from long-term bonds to short-term bills, which the Fed then absorbs. This is a backdoor way to manage rates without formal QE.

Beyond its official mandates of price stability and employment, the Fed's primary, unspoken obligation is ensuring the Treasury market functions smoothly. The Fed consistently intervenes to quell bond market volatility, prioritizing the government's ability to fund itself over its other stated goals when financial conditions tighten severely.

Over the past few years, the Treasury Department and the Federal Reserve have been working at cross-purposes. While the Fed attempted to remove liquidity from the system via quantitative tightening, the Treasury effectively reinjected it by drawing down its reverse repo facility and focusing issuance on T-bills.

The Treasury is funding the purchase of long-duration bonds by issuing short-duration T-bills. This action, dubbed a "fiscal operation twist," removes duration from the market and has a stimulative effect similar to the Fed's QE, but is led by the fiscal authority.

The current Treasury buybacks, funded by T-bill issuance, set the stage for a more extreme policy: direct debt monetization. This would involve the Federal Reserve purchasing the newly issued T-bills directly from the Treasury, effectively printing money to finance fiscal operations.