Stock index futures pointed to a lower open on Monday as Chinese equities dropped sharply and commodities fell on concerns that asset prices have run ahead of the economic realities.

Financial shares also pulled back after a recent rally, with American International Group Inc falling nearly 10 percent, and Barron's recommending investors take profits in Citigroup Inc , which dropped 3 percent before the bell.

The Shanghai Composite Index <.SSEC> dived 6.7 percent to a three-month closing low and recorded its second-biggest monthly loss in 15 years on worries that corporate earnings failed to justify stock valuations.

It (China) is weighing on our market open, said Marc Pado, U.S. market strategist at Cantor Fitzgerald & Co in San Francisco. Pado said he expects the market to consolidate heading into the traditionally weak month of September.

Recent falls in China equities have caused jitters in stock markets around the world as some investors say prices are too high after a strong run-up. The S&P 500 index <.SPX> is up around 50 percent since a hitting a trough in early March.

S&P 500 futures fell 7.4 points and were below 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 lost 76 points and Nasdaq 100 futures dropped 13.75 points.

Traders cited the sell-off in Chinese equities for a fall in the price of oil and other commodities. Oil dropped 3 percent to below $71 a barrel, and metals prices slid.

In New York, shares in natural resource companies sold off before the bell. Exxon Mobil Corp dropped 1.3 percent to $69.18 while miner Freeport-McMoRan Copper & Gold Inc Inc fell 3 percent to $63.50.

The Select Sector SPDR Financial ETF fell 1.6 percent.

Oilfield service company Baker Hughes Inc said it will buy smaller competitor BJ Services Co for $5.5 billion in stock and cash, sending BJ's shares up 11.5 percent to $17.20 before the bell.

A regional survey on Monday is expected to show manufacturing in the U.S. Midwest improved again in August after last month posting its strongest gain since September. The report is the first in a busy week for economic data ending with the closely watched monthly jobs report on Friday.

Economists in a Reuters poll forecast that the Chicago PMI index rose to 48 points in August from 43.4 points in July. The report is due at 9.45 a.m.

(Reporting by Edward Krudy; Editing by Padraic Cassidy)