Forced margin, stop-loss, and ruin risk in 2020

When a stop does not close the account risk

In a rare disorderly break, a stop-loss or a lighter hedge can still leave a futures or short-option book exposed to an account-level setback. A stop-loss is a pre-commitment that bounds how much a position may lose before and during a trade, without assuming the bound will hold in a disorderly print.

Purchased calls and puts were presented as the only complete protection for those books when stops and other hedges prove insufficient.

A black swan shock is a rare, disorderly break in which ordinary filters fail together and historical extremes stop being a reliable ceiling. Treating the largest past move as a ceiling is a false bound: a market can travel farther and faster than it ever has.

Margin that turns a voluntary book into forced flow

Margin management means keeping size and cash inside exchange and broker requirements so a volatility spike cannot turn a voluntary book into forced buying or selling.

When an exchange raises margin during a volatility spike, traders already short of cash can be forced to buy or sell because they must meet the requirement, not because they want the trade. That forced flow showed up as heavy selling in crude oil below 20 per barrel and in the S&P 500 below 2,200.

Forced liquidation is buying or selling that occurs because margin or cash pressure requires it, not because the trader wants the trade.

Unused equity as a position

Unused buying power is itself a position: traders already fully allocated into the March 2020 break were stuck defending rather than acting when prices cheapened.

Unused equity is cash and uncommitted buying power treated as a position, because a fully used book can only play defense when prices finally cheapen.

Ruin after a short run of forced exits

Risk of ruin is the chance that one shock, or a short run of forced exits, reduces equity enough to end the account or erase years of prior progress. Correlated liquidation is a ruin risk of its own: when many holders exit together, positions that looked separate can fail at the same time.

A method that usually works can still produce a large drawdown in a shock, while a method that usually fails can appear to work then. That reversal is not a reason to adopt the usually failing method.