Yahoo! Inc. recorded $165 million in gains in the second quarter from steps the Web portal took to guard against swings in the Japanese yen, bringing its total benefit from such currency hedges to $438 million.

After using forward contracts to reduce foreign-exchange risk related to its stake in Yahoo Japan Corp., the company had recorded a pretax gain of $270 million in the first quarter and $3 million for last year, Sunnyvale, California-based Yahoo said in a regulatory filing.

Chief Executive Officer Marissa Mayer has benefited from the company’s investments in Yahoo Japan and Alibaba Group Holding Ltd., the Chinese online marketplace that may hold an initial public offering by the end of the year. Mayer decided to hedge against the yen last December, with forward contracts that mature at nine to 15 months, the company said in the filing.

Forward contracts give the right to purchase a currency at a certain price at a prearranged date, helping protect the holder against a change in a currency’s value.

“If the Japanese yen depreciates at maturity from the forward contract execution rates, we will receive a cash settlement, which may be material,” Yahoo said. “We have elected to apply net investment hedge accounting and expect the hedges to be effective.”

The estimated value of the forward contracts was $3.5 billion at the end of June, according to the filing. The fair value of the assets was included in prepaid expenses and other current assets on the company’s balance sheet.

Yahoo also said it agreed to pay $40 million in cash as well as stock-based compensation worth $70 million to Tumblr Inc. founder David Karp over the next four years to retain him after buying his blogging website in June. It acquired nine other companies in the first half of 2013 totaling $54 million, according to the filing.

The shares of Yahoo gained less than 1 percent to $27.48 at the close in New York. The stock has advanced 38 percent this year, compared with a 19 percent gain for the Standard & Poor’s 500 Index.