[low tide water liquidity drought boats]Wikimedia Commons Brevan Howard, one of the world's biggest hedge funds, is said to be preparing for more investors to withdraw funds. The move comes as the firm's performance stagnates and two of its star traders have left to start competing firms. The details of the plans were shared by three people with knowledge of the matter who declined to be named. The firm cut staff numbers and closed several of its funds last year, and the planning is now said to be in preparation for a "worst-case scenario" in case a significant number of investors ask for redemptions, according to one of the people. Brevan's contingency planning, which is aimed at ensuring that it can withstand outflows, includes a scenario in which assets fall by as much as 40%, two of the people said. There's no indication that the firm will lose that amount, and contingency planning by funds that would have to unwind investments in case of redemptions isn't unusual. Brevan Howard, best known for its flagship fund, posted a loss of 2% last year and was down 1.8% through April this year, according to a fourth person familiar with the returns. The fund hasn't reported a year of gains since 2013, the Financial Times reported in May. The firm manages about $20 billion, another person said. That's down by about $3.7 billion from the assets reported by the Hedge Fund Intelligence Global Billion Dollar Club at the start of the year. One of the people said the firm's assets had fallen further. Brevan was the 19th-biggest hedge fund in the world at the start of the year, according to the ranking. The drop in assets is coming mostly from investors who are pulling their money, upset with the firm's performance and high fees, according to the people. A representative at Peregrine Communications, which represents Brevan Howard, said the firm has no contingency plan. Large funds often plan ahead of time how they will unwind assets if need be, especially in cases in which other investors may sell those same assets first, further depressing the price. [London Big Ben]Wikimedia CommonsStill, the preparation for such a decline represents a changing tide for Brevan, a titan in the industry that as recently as 2013 managed about $40 billion. Brevan isn't the only large hedge fund to face outflows or investor concern following underperformance, but its prominence as one of the preeminent "macro" hedge funds in Europe signals the challenges the industry is facing at large. Macro funds, which bet on economic events, lost 3.2% last year and are up 0.6% this year through May, according to eVestment. Brevan Howard has opened up retail "alternative" mutual funds in Europe that could help shore up the investor base. But the firm is increasingly facing headwinds. One of its star traders, Ben Melkman, recently left to start his own macro hedge fund in New York and is expected to take investors with him for his new fund, which is targeting $400 million at its initial launch. Another one-time Brevan star, Chris Rokos, started his own firm last year and has already raised at least $3.5 billion. _Note: This article has been updated to add a comment from Brevan Howard's public-relations firm._ NOW WATCH: FORMER GREEK FINANCE MINISTER: How I dealt with stress when Greece nearly defaulted