Running Gross And Net Exposure

A book with $60m long and $60m short looks, on one number, like it is doing nothing: net exposure is zero. On another number it is running $120m of positions that can each individually go wrong. Both numbers are true and neither tells the whole story on its own — that is the entire reason desks track both.

Two questions, two numbers

Net exposure is longs minus shorts, and it answers "which way is this book betting on the market." A book that is $60m long and $60m short is net flat — a broad market rally or selloff should move the longs and shorts against each other and roughly cancel.

Gross exposure is longs plus shorts (absolute value), and it answers "how much capital is actually at risk across individual positions." That same $60m/$60m book has $120m of gross — 120% of book equity if the book is $100m — and every one of those 120 million dollars is exposed to its own name-specific risk: an earnings miss, a fraud, a short squeeze. Net exposure being zero says nothing about any of that.

Worked example

A $100m long-short book targets net exposure between -10% and +20% and gross exposure no more than 180% of NAV.

	Longs	Shorts	Net	Gross
Monday	$78m	$62m	+$16m (+16%)	$140m (140%)
Thursday	$95m	$88m	+$7m (+7%)	$183m (183%)

By Thursday, net exposure has actually fallen — the book looks "less directional" on that one number. But gross has risen from 140% to 183%, past the cap, because both sides were built up (more longs added, more shorts added) rather than one side trimmed. The book is not more cautious on Thursday; it is running more single-name risk on both sides simultaneously, and the low net number is hiding that.

The fix is not to reduce net — net is already inside its band. It is to trim gross: cut some of the weakest longs and weakest shorts symmetrically until gross is back under 180%, without disturbing the net directional stance the book actually wants.

Why both limits are necessary

A cap on net alone lets a book quietly lever up as long as it adds roughly equal amounts to both sides — the net number stays calm while the book becomes far more sensitive to a spike in correlations or a liquidity event that hits longs and shorts together (which happens routinely in a broad market dislocation, when "flight to safety" hits low-quality shorts and high-quality longs in opposite, reinforcing directions). A cap on gross alone says nothing about whether the book is secretly making a large directional bet. Desks that only watch one of the two are, by construction, blind to the risk the other one is built to catch.