Actually, if you look at it this way, Carl Icahn is doing worse than Bill Ackman

Part of measuring on Wall Street is finding exactly the right stick.

There are many options - returns, assets under management, what have you. Another is net asset value (NAV) and that's what we're going to talk about today.

Because by that metric, Bill Ackman, who has had a notoriously bad year thanks to his short bet on Herbalife and his long slog with Valeant Pharmaceuticals, actually has a leg up on his long-time nemesis.

On Thursday morning Icahn Enterprises, the conglomerate founded by billionaire investor Carl Icahn, posted a loss. Most of it was derived from a truly dismal year for $1.7 billion fund Icahn Investments, which is down 18% for the first six months of the year after going short on the market up to its eyeballs.

The Sunday before, billionaire Bill Ackman of hedge fund Pershing Square, also reported dismal returns for the quarter. Pershing is also down 18% for the first six months of the year.

Go figure. The matching losses are a funny coincidence since the two investors are frenemies at best, and at worst each other's archenemy. Icahn infamously took the other side of Ackman's very public three year short of Herbalife, a nutritional supplement company. Icahn owns 18.3% of the company's shares.

Since these two men have such similar terrible returns by one metric, it's worth it to look at NAV to better understand who is winning 2016. NAV is calculated by deducting a fund's liabilities from the combined value of all its shares, the dividing that by the number of issued shares.

Basically, if your book were sliced into pieces, this is what it would be worth.

Ackman ended the first quarter with an NAV of $17.81 and by June 30 it was sitting at $16.54 - about a 7% drop. You can see the weekly change in Pershing's public fund here.

Meanwhile, Icahn ended the first quarter with an NAV of $37.98 and by June 30 it had fallen to $29.90 - a much worse 21% decline.

Given Icahn's more precipitous drop, by this metric (this one metric) Ackman is beating Icahn. The biggest killer of NAV for Icahn's portfolio was CVR Energy, which is down over 65% year to date.

From Icahn's Q2 presentation: