U.S. stocks rose, sending benchmark indexes toward their biggest gains in 2012, on speculation global policy makers will act to revive a slowing economy.

Stocks rose for a third day after the S&P 500 fell as much as 9.9 percent from this year’s peak in April amid concern about a global slowdown. Earlier this week, the index traded at 12.9 times reported earnings, the cheapest valuation in six months, according to data.

Equities gained as European Central Bank President Mario Draghi said officials stand ready to act as the euro region’s growth outlook worsens. Federal Reserve Bank of Atlanta PresidentDennis Lockhart said extending Operation Twist, the program to lengthen maturities of debt on the central bank’s balance sheet, is an “option on the table.” The Fed will publish its Beige Book survey of business conditions in 12 national districts today.

All 10 groups in the S&P 500 rose today as commodity, financial and technology shares had the biggest gains. Bank of America (ВАС) increased 7.5 percent, the most since January, to $7.46. Caterpillar (САТ) added 3.3 percent to $86.37, while Hewlett-Packard (HPQ) jumped 2.9 percent to $22.31.

Iron Mountain Inc. surged 10 percent, the most in the S&P 500, to $31.35. The document-storage company approved a plan to convert to a real-estate investment trust and increased its quarterly dividend by 8 percent.

Chesapeake Energy jumped 7.2 percent to $18.22. The energy explorer, facing a $22 billion cash-flow shortfall after natural-gas prices touched a decade low, is discussing selling its entire stake in Chesapeake Midstream Partners LP and other pipeline assets, said two people with knowledge of the matter. The negotiations may lead to a deal within days and could also fall apart, the people said.

Home Depot (HD) rose 2.8 percent to $50.29. The timing of its share repurchases will not have a material impact on the diluted earnings per share in that period, the Atlanta-based retailer said today in a statement.