Buying Russian options as protection from plunging stocks will probably be unprofitable because contract prices have surged after the nation's equity market lost one-quarter of its value this week, investors said Thursday.

"It's like buying car insurance when you live in the worst part of town," said Douglass Welch, head of derivatives sales at Troika Dialog in London.

Wider share-price swings drive up the cost of calls and puts, which investors can use to eliminate the risk of stock losses. The 30-day volatility of the MICEX Index jumped to 79.02 on Wednesday, the highest since at least 2001. Implied volatility, a gauge of expectations for future stock swings, on the RTS Index has reached about 100, Welch said.

"It's not cheap at all," said Ian Hague, founding partner of Firebird Management in New York.

Put options give the right to sell a security for a certain amount by a given date. Calls convey the right to buy. Investors use the contracts to guard against fluctuations in the price of securities they own, speculate on share-price moves or bet that volatility will increase or decrease. Volatility is a measure of the magnitude of gains and losses for a given security or index. The higher implied volatility in Russia means that investors who buy puts to bet on slumps or calls to bet on rebounds will have to pay more.

"We still have a lot of people trying to buy the bounce," Welch said. "Unless you're extremely right, it's just not profitable to buy these products."