Activist Clint Carlson is probably feeling a bit run down today after Vitamin Shoppe Inc. VSI, one of his holdings, fell more than 30% after the specialty retailer posted second-quarter earnings 16 cents below estimates and said it's still struggling to build a robust business plan.

"Given the unprecedented level of volatility in the market and the potential increase in variability of the Company's results due to the number of initiatives being launched in the back half of the year, the Company has reset its 2017 outlook and is modifying its approach to guidance. The Company is providing guidance around the key levers that drive the business instead of providing specific EPS guidance," the company said in a press release accompanying the results.

The shares traded down 36.5% at $6.10 in Wednesday action. If it holds where it is it will be the stock's -worst trading day ever.

Carlson and his eponymous fund bought into the company in April 2015 and reached an arrangement whereby each side would nominate a director on a new, expanded board and he would, "abide by certain customary standstill provisions." In February, the parties amended the 2015 agreement, inking a new pact to add two new mutually agreed upon directors and also to re-nominate Carlson's director representative from last year.

The investor cut his teeth as the head of risk arbitrage at Bass Brothers, and from 1985 to 1988 co-managed a risk arbitrage fund at Maxxam Group.

Carlson started his fund in 1993 and has launched 30 campaigns, at 29 companies since then. He largely avoids proxy fights, preferring to negotiate board representation and work behind the scenes.

His fund also is unusual in that it has a broad portfolio, currently owning more than 230 different stocks. Compare that to a Bill Ackman at Pershing Square, who generally holds fewer than 10 different names in his fund at any given time.

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