The Swiss National Bank Removed a Floor and Brokers Failed Within Minutes
In January 2015 Switzerland abandoned its cap on the franc without warning. The currency moved so far so fast that leveraged clients went past zero and their brokers absorbed the difference.
The Policy
Following the eurozone crisis, safe haven demand had pushed the Swiss franc sharply higher, damaging Swiss exporters. In 2011 the Swiss National Bank announced it would not allow the euro to fall below 1.20 francs, and committed to buying foreign currency in unlimited quantities to enforce it.
The commitment was credible and it worked. The rate held near the floor for over three years, and market participants treated the level as effectively guaranteed.
The Removal
On 15 January 2015 the central bank announced without warning that the floor was discontinued. The franc appreciated dramatically within minutes, with the euro falling well below the former floor before partially recovering.
Maintaining the floor had required accumulating enormous foreign currency reserves, and expectations of further European monetary easing implied the cost would grow. The bank concluded the policy was no longer sustainable.
The absence of warning was deliberate. Announcing an intention to remove a floor would have triggered exactly the move the announcement was meant to manage.
Why Stop Losses Failed
The consequence that matters for market structure concerns leveraged retail trading. Foreign exchange brokers offered high leverage, and clients used stop loss orders intended to close positions automatically at defined levels.
A stop loss is not a guarantee of price. It is an instruction to execute at the market once a level is reached. If price gaps through the level with no liquidity in between, execution occurs wherever the market next trades, which can be far away.
Clients positioned against the franc found their stops executed at prices dramatically worse than intended. With high leverage, losses exceeded account equity entirely.
Negative Balances
That produced the structural problem. Clients owed more than they had deposited. Brokers were legally entitled to pursue them and practically unable to collect from retail customers who did not have the money.
Several brokers failed as a result. One prominent firm entered insolvency, and another required an emergency loan to continue operating.
What Changed
Regulators in several jurisdictions subsequently restricted leverage available to retail clients and required negative balance protection, meaning a client cannot lose more than they deposit.
That protection moves the tail risk from the client to the broker, which is where it is better held, since brokers can capitalise against it and diversify across clients.
The General Lesson
Two points transfer. A central bank commitment is credible until the cost of maintaining it exceeds what the institution will bear, and it will not warn you before that point.
And risk controls that depend on continuous liquidity fail precisely in the events they exist to protect against. A stop loss works in normal markets and does not work in a gap, which is the only time it is genuinely needed.
The Bottom Line
The floor held until it did not, and stop losses could not execute in the gap. Any control that assumes you can trade at your chosen level assumes a market that exists on the worst day.