U.S. stocks fell, sending the Standard & Poor’s 500 Index to its lowest level in two months, as Greece’s struggle to form a new government intensified concern about a euro exit and deepening of the region’s debt crisis.

American equities joined a global slump as Greek stocks fell to the lowest in two decades. Greece’s leaders meet for a second day to try to form a government after New Democracy’s Antonis Samaras failed to forge an agreement following an election that raised questions about the euro membership.

The attempt to form a government now passes to Alexis Tsipras, the head of Syriza. Tsipras ran on a pledge to overturn Greece’s bailout, helping Syriza emerge as the country’s second- most voted party. He has said he will seek to form a coalition with other parties that favor reversing the 130 billion-euro bailout, the country’s second aid package, which came after Greece carried out the biggest debt restructuring in history.

All 10 groups in gauge retreated today as consumer discretionary and commodity shares had the biggest losses. The Morgan Stanley Cyclical Index of companies most-tied to the economy decreased 1.5 percent. Caterpillar (САТ), the largest maker of construction equipment, slid 2 percent to $95.21. Alcoa (АА), the biggest U.S. aluminum producer, fell 2 percent to $9.15. Bank of America (ВАС) sank 2.3 percent to $7.78.

Discovery Communications Inc. retreated 6.4 percent to $50.60. The owner of cable networks such as Animal Planet and TLC reported a 28 percent decline in first-quarter profit after a one-time gain last year on Oprah Winfrey’s network, OWN.

McDonald’s (MCD) lost 1.4 percent to $94.16. Sales at stores open at least 13 months rose 3.3 percent worldwide last month, trailing estimates, as sales growth slowed in the U.S. Analysts projected a gain of 4.3 percent, the average of 13 estimates compiled by Consensus Metrix. Sales in the U.S. advanced 3.3 percent. Analysts estimated an increase of 5.2 percent.