Single-name event risk: the overnight halving

The seed of this module is one sentence: a stock can halve overnight, and an index cannot. This lesson is that sentence, taken seriously.

Why only equities carries this lesson

An index absorbs its casualties - the failed constituent shrinks and is replaced, and the index prints a bad day. A commodity is a molecule - it cannot be discovered to have been lying about its accounts. A single company can: fraud surfaces, trials fail, contracts vanish, guidance detonates - and the repricing routinely happens through a halt or an overnight gap, from a price to half of it or less, with no tradeable path between. Module 1's residual claim is the mechanism: when the business's story breaks, the equity absorbs the whole break, first.

Why the stop and the gap-size both miss it

• The stop prices continuous movement; the halving arrives through a halt or a gap - there is no path on which the stop executes anywhere near itself.
• Even gap sizing assumed a distance - the earnings history, doubled. The halving ignores histories: it is the tail beyond every estimated distance, and it does not book appointments.
• Conviction is not a defence: the halvings land on names with the most convinced holders - the conviction is why the position was big, and the size is why the event was ruinous.

The cap, and the two-constraint rule completed

The defence is embarrassingly simple: no name exceeds a fixed share of the account - a common institutional band is mid-single-digit percent - so that even a total loss is a survivable year, not an ending. Lesson 2's rule completes here: size to the smaller of the risk-budget answer and the cap. For large accounts the budget binds; for concentrated convictions the cap does - and it must, because it is the only line in the whole risk plan that still works when the price teleports. Ownership's freedom, one last time: nothing stops you betting the account on one story. The cap is you, stopping you, in writing, while it is still cheap.