U.S. stock index futures pointed to a lower open on Wall Street on Wednesday, as investors were poised to pocket a portion of their recent lofty gains ahead of key macroeconomic data.

At 4:50 a.m. EDT, futures for the S&P 500 were down 0.5 percent, Dow Jones futures were down 0.3 percent and Nasdaq 100 futures were down 0.4 percent.

Sovereign wealth fund China Investment Corp said it is buying into a $2.2 billion common stock offering by Morgan Stanley because it is confident in the Wall Street bank's prospects. Morgan Stanley said the proceeds of the offering, priced on Tuesday at $27.44 a share, would bring it closer to repaying $10 billion it borrowed under the U.S. Treasury's Troubled Asset Relief Program.

Morgan Stanley's stock traded in Frankfurt was up 4.4 percent.

U.S. auto sales fell nearly 34 percent in May from a year earlier, but aggressive discounting helped steady results for the battered industry, according to monthly results released on Tuesday. Industry-wide auto sales for the month reached nearly 10 million units on an annualized basis -- a better result than most economists had expected with the industry reeling from auto bankruptcies.

General Motors Corp said on Tuesday it reached a tentative deal to sell its Hummer brand to a privately held Chinese heavy machinery maker, part of an effort to drop four unprofitable vehicle lines and leave bankruptcy as a leaner company. GM, a day after filing for bankruptcy, said in a statement that it reached a memorandum of understanding with Sichuan Tengzhong Heavy Industrial Machinery Co for the sale. Tengzhong said it will retain Hummer's senior management and operational team.

European stocks <.FTEU3> were down 1 percent in morning trade, retreating from a five-month high reached during the session on Tuesday, as investors booked recent gains on banking and mining shares ahead of U.S. macroeconomic data due later in the session.

Investors were bracing for the ADP private sector employment data for May, due at 1215 GMT, the ISM non-manufacturing business activity index, due at 1400 GMT, and monthly factory orders, also due at 1400 GMT.

The dollar hit a five-month low against the euro on Wednesday and hovered near its lowest of the year against a currency basket as traders continued to dump the U.S. currency for higher-risk ones due to ongoing speculation the global economy may be recovering.

A U.S. Court of Appeals agreed on Tuesday to hear a challenge to Chrysler LLC's sale of most of its assets to a group led by Italian automaker Fiat , in a move that could potentially delay the deal. The federal circuit court granted a request by a group of Indiana pension funds that hold a small portion of Chrysler's secured debt to stay the sale order to allow the circuit court to hear the expedited appeal.

U.S. stocks rose for a fourth straight day on Tuesday as an upbeat report on home sales bolstered hopes for an economic recovery as well as shares in construction companies. But a sell-off in financials on worries about the dilutive impact of recent stock offerings limited a broader advance.

The Dow Jones industrial average <.DJI> added 19.43 points, or 0.22 percent, to 8,740.87. The Standard & Poor's 500 Index <.SPX> gained 1.87 points, or 0.20 percent, to 944.74. The Nasdaq Composite Index <.IXIC> rose 8.12 points, or 0.44 percent, to 1,836.80.

Since reaching a floor in early March, the Dow is up 35.1 percent and the S&P is up 41.7 percent.

(Reporting by Blaise Robinson; Editing by Hans Peters)