ZURICH--The Swiss National Bank's first-half interim profit was 16.1 billion Swiss francs ($17.7 billion) thanks to foreign-currency and gold prices.

Foreign-currency positions contributed around 12.6 billion francs. There was a "valuation gain" of 3.5 billion francs on gold holdings which were unchanged by volume, the Swiss central bank's said in a statement Thursday.

Equity securities and instruments added 2.5 billion francs, it said.

"The financial result depends largely on developments in the gold, foreign exchange and capital markets," it said. "Strong fluctuations are to be expected and only provisional conclusions are possible as regards the annual result."

First-quarter profit was 4.4 billion francs.

Write to Neil MacLucas at neil.maclucas@wsj.com

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