Stock index futures indicated a lower open on Wednesday on concern over a rising Japanese yen, a signal that free-flowing liquidity that has fueled gains in global equity markets could dry up.

In takeover news, Rupert Murdoch told Reuters on Wednesday he had no plan to raise his News Corp.'s bid for Dow Jones & Co. Inc. and said he is waiting for final approval of the proposed acquisition from the Bancroft family, which controls the publisher of the Wall Street Journal.

A weak Japanese currency has allowed investors to borrow cheaply in yen to buy higher-yielding assets elsewhere, a practice known as carry trade. The yen rose on Wednesday against the dollar and euro.

What's been driving the market is this massive liquidity of people making one-way bets on a weaker yen, said Paul Mendelsohn, chief investment strategist at Windham Financial Services in Charlotte, Vermont. The last time people unwound carry trades, it caused the market to drop in February. That's risk No. 1.

S&P 500 futures were up 3 points but below fair value, a mathematical formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract.

Dow Jones industrial average futures rose 11 points, and Nasdaq 100 futures were up 3.25 points.

Companies set to report quarterly results before the opening bell include packaged food maker ConAgra Foods and spice seller McCormick & Co.

On the economic agenda, the government will report May durable goods data. Economist forecast orders for long-lasting manufactured goods to have fallen 1 percent last month.

On Tuesday, the Dow Jones industrial average slipped 0.11 percent to end at 13,337.66. The Standard & Poor's 500 Index dropped 0.32 percent and the Nasdaq Composite Index declined 0.11 percent.