The US Treasury's checking account at the Federal Reserve; when it rises, bank reserves fall by the same amount, which makes it a driver of system liquidity.
The TGA sits on the liability side of the Fed's balance sheet alongside bank-reserves. Tax receipts and debt issuance move money from the private sector into the TGA, draining reserves. Government spending moves it back out, adding reserves.
Liquidity watchers track the TGA because large swings can tighten or loosen funding conditions independently of policy. A post-debt-ceiling rebuild of several hundred billion dollars in a few weeks is a genuine liquidity drain.
Example: the TGA rises from $300 billion to $750 billion over six weeks of heavy bill issuance. Reserves fall by roughly the portion not funded out of the overnight-reverse-repo-facility, and GC repo starts printing a few basis points firmer.
Original diagrams for the ideas on this page. Illustrative, not real market data.
The bid-ask spread. Buy orders sit below, sell orders above, and the gap between the best bid (50.01) and best ask (50.04) is the spread you pay to cross. Bar length shows the size resting at each price.
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