From the Collaborative Bond and Money Market Data Portal
System Open Market Account (SOMA) holdings are the portfolio of securities and related assets owned by the U.S. Federal Reserve, managed by the Federal Reserve Bank of New York on behalf of the Federal Open Market Committee (FOMC), and used to implement monetary policy. They consist primarily of U.S. Treasury securities (bills, notes, bonds, TIPS, FRNs), agency debt, and agency mortgage‑backed securities, along with a smaller foreign‑currency portfolio (notably euro and yen assets) and associated repurchase and reverse‑repurchase positions.
Impact on money markets:
SOMA operations are a key mechanism for controlling short‑term interest rates, as the size and composition of the portfolio determine the level of reserves in the banking system and the need for complementary tools such as overnight reverse repo (ON RRP) facilities.
Expansions in SOMA holdings typically increase reserve balances, which tends to ease money market conditions and pull overnight rates toward the lower part of the policy corridor, while balance‑sheet runoff drains reserves and can tighten conditions if not offset.
The securities in SOMA also underpin the Fed’s securities‑lending and repo activities, which influence collateral availability, repo specials, and therefore the transmission of policy rates into Treasury bills, GC repo, and other money market benchmarks.
Impact on bond markets:
When SOMA holdings increase through large‑scale purchases (e.g., QE), the Fed removes duration and credit risk from the market, typically compressing term premia, lowering Treasury and agency MBS yields, and flattening parts of the curve.
By holding a material share of outstanding issues, SOMA reduces free float in specific CUSIPs, which can affect on‑the‑run/off‑the‑run spreads, specials in the repo market, and liquidity conditions for certain benchmarks.
Changes in the reinvestment and runoff policy (e.g., caps on redemptions, active sales vs passive runoff) signal the stance of policy normalization and can move yield levels and curve shape as investors re‑price expected net supply.
In practice, dealers and asset managers track SOMA holdings closely because shifts in its size, composition, and reinvestment policy directly shape both term structure pricing in the bond market and the level and stability of money market rates.
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