The SNB's US equity portfolio rose to a record $141 billion in December, reflecting a rally in the stock market.

The SNB, which invests 20 per cent of its reserves in stocks, held shares in 2490 companies as of December 31, according to a filing with the US Securities and Exchange Commission on Friday.

High-profile holdings include Apple Inc、 Amazon.Com IncAnd even GameStop Corp.. The latter's share price fluctuated sharply in the standoff between retail investors and Wall Street professionals, prompting Treasury Secretary Janet Yellen to call for an investigation.

The SNB has accumulated a large amount of foreign exchange reserves by intervening in the foreign exchange market to ease the upward pressure on the Swiss franc and resist deflation. The United States designated Switzerland as a currency manipulator last year.

The SNB's investments are based on relevant indices and are designed to serve monetary policy objectives rather than generate profits.

A SNB spokesman declined to comment on the filing.