This risk-free arbitrage trade locked in a small profit for the institutional investor and kept the SuperUnit market price in line with its underlying value.

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But my best guess is that someone on that risk free arbitrage desk moved from risk free pure arbitrage into very definitely not risk free time arbitrage, or speculation as we should call it, then the market moved against his bet.

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However, one of this summer's best investment tips, currency arbitrage, is risk-free.

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But unlike closed-end funds, if SuperUnits developed a discount to its underlying securities value, then institutional investors could arbitrage the units and profit risk-free.

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