Calendar spreads · Market depth · Exit capacity
Amaranth Advisors Anarchy
A spread can be market-neutral in direction and still be catastrophically exposed to curve shape, position size, and the impossibility of exit.
CENTRAL QUESTION
When does a relative-value trade become the market it is supposed to observe?
01 / THESIS
The argument
Amaranth’s natural-gas book was built around differences between futures maturities, particularly winter and non-winter contracts. The trade could be described as relative value rather than outright direction, but its scale made that distinction misleading. Exposure to the curve’s shape was concentrated, leveraged, and too large to exit without affecting the prices used to value it.
The U.S. Senate investigation concluded that Amaranth’s speculative trading dominated parts of the market and contributed to extreme spread levels. When the spreads reversed in 2006, the portfolio’s mark-to-market losses, margin demands, and limited exit capacity reinforced one another.
02 / CHRONOLOGY
The sequence
- 2005—2006
The fund’s natural-gas positions expand across regulated and electronic markets.
- SUMMER 2006
Winter/summer spreads reach extreme levels while Amaranth represents a large share of relevant open interest and trading.
- SEP 2006
Spread relationships reverse; losses and variation-margin needs accelerate.
- AFTERMATH
The energy portfolio is transferred and the fund winds down; regulators pursue manipulation claims.
03 / MECHANISM
How the failure compounds
Calendar-spread risk
A long contract and short contract reduce outright price exposure but create leveraged sensitivity to changes in curve shape.
Endogenous liquidity
Observed market depth is not available to a seller whose position is itself a material share of the market.
Margin path
Futures settle daily. A trade that may converge at expiry can fail earlier if variation margin exceeds available liquidity.
04 / JUDGMENT
What survives the case
The useful denominator for position sizing is not fund NAV alone. It is executable market depth under stress. Risk should be expressed as days to liquidate, percentage of open interest, expected slippage, and collateral required after an adverse curve move.
Relative-value language can create false comfort. The portfolio did not need the level of natural gas to be wrong; it needed a particular relationship between contracts to persist long enough for the fund to remain solvent.
EVIDENTIARY LIMIT
The Senate staff report and CFTC action address overlapping but distinct market-conduct and risk questions. This brief does not independently determine manipulation liability.
05 / SOURCE DOCKET
Follow the evidence.
VERSION 1.0 · EXPANDED SEPTEMBER 7, 2026 · MATERIAL CORRECTIONS WILL BE RECORDED ON THIS PAGE.