Stock index futures pointed to a higher open on Friday on optimism the economic slump is waning, but a reassessment of the recent sharp market run-up could keep gains in check.

The S&P 500 closed out its best month in nine years, gaining 9.4 percent for April on growing hopes the worst was over for the financial sector and recession-hit economy.

There has been a firm bid under the market, said Barry Ritholtz, chief market strategist at Fusion IQ in New York. We've rallied right up to some major resistance, and you have to assume that at some point the market is going to have to catch its breath.

Among companies expected to report earnings are Chevron Corp , the second largest U.S. oil company, MasterCard Inc , the world's second largest credit card network, and Clorox Co , which makes the namesake bleach, Glad trash bags and Brita water filters.

Shares of MasterCard were down 1.3 percent at $181.00 in premarket trade.

Aon Corp , the world's largest insurance broker, reported a rise in profit, helped by restructuring efforts, but revenue slipped as investment income fell.

On the data front, new orders received by U.S. factories in March are expected to have fallen 0.6 percent from a year earlier after rising 1.8 percent in February, according to the average forecast of 52 economists polled by Reuters.

Other data on tap for the morning includes readings on the Institute for Supply Management's April manufacturing index and the final look at April consumer sentiment.

S&P 500 futures rose 3.80 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures climbed 44 points, and Nasdaq 100 futures added 5.50 points.

Data is also expected to show that U.S. auto sales plunged to their lowest levels in nearly 30 years in April, with automakers expected to post declines of at least 30 percent from a year earlier.

The data comes a day after U.S. automaker Chrysler LLC filed for bankruptcy and entered into an industry-changing deal with Italy's Fiat SpA .

Investors have been encouraged by better-than-expected first-quarter results that added to hopes companies are also starting to hit bottom.

Of the 280 companies in the S&P 500 that have reported earnings to date, 65 percent topped analysts' estimates, according to data compiled by Thomson Reuters as of Thursday. However, many of the analysts' estimates had been reduced to reflect the current economic slump.

On the downside, shares of Hartford Financial Services Group Inc lost 12.8 percent to $10.00 before the opening bell. The insurance company posted a first-quarter loss after the close on Thursday.

MetLife Inc fell in extended trade after the close. The largest U.S. life insurer also recorded a loss as its investment income dropped.

Shares of Citigroup Inc were up 3.9 percent at $3.17 ahead of the opening bell. Sumitomo Mitsui Financial Group Inc <8316.T> will buy the bank's Japanese broker and key investment banking units for $5.9 billion.

Also in the banking sector, Bank of America Corp's board is not planning to remove Chief Executive Kenneth Lewis after he was ousted as chairman, the Journal reported.

The Dow and S&P 500 fell on Thursday after Chrysler's bankruptcy filing undercut optimism about upbeat corporate profits and reassuring job market data.

(Reporting by Leah Schnurr)