Stock futures fell sharply Wednesday, a day after major indexes posted their biggest losses in months. Investors remain concerned about European debt problems.

European markets dropped as investors remain uncertain about whether a $144 billion aid package for Greece will help stem the growing debt crisis. German Chancellor Angela Merkel asked her country's lawmakers to rush the approval of Germany's $29.3 billion share of the Greek rescue program.

Stocks plunged around the world Tuesday as fears escalated that Europe might fail to contain Greece's debt problems. The Dow Jones industrial average fell 225 points, its biggest drop in three months.

Investors worry that Europe would have trouble bailing out larger countries like Spain and Portugal because the continent's governments spent so much supporting Greece. There are also concerns that the large debt among European nations could upend a global economic recovery.

Analysts have said that the problems, over the long term, could lead to a collapse of the euro. Sixteen countries use the common currency. The euro fell against the dollar, hitting its lowest level in 14 months.

Market volatility has increased over the past week as investors' focus alternates between worries about European debt problems and further signs of U.S. economic growth. Tuesday was the fifth time in six sessions the Dow has surged or retreated by triple digits.

Investors looking for continued signs of a domestic recovery received another encouraging sign on employment. Payroll company ADP said private employers added 32,000 jobs last month.

A separate report due out later is expected to show the service sector expanded again in April.

Ahead of the opening bell, Dow Jones industrial average futures fell 74, or 0.7 percent, to 10,818. Standard & Poor's 500 index futures fell 11.20, or 1 percent, to 1,161.20, while Nasdaq 100 index futures fell 19.50, or 1 percent, to 1,950.00.

The Institute for Supply Management's service-sector index likely rose to 56 last month from 55.4 in March, according to economists polled by Thomson Reuters. Any reading above 50 indicates growth.

Further expansion of the sector would indicate the largest part of the economy continues to rebound. The service sector accounts for 80 percent of the nation's work force, excluding farmworkers.

High unemployment is considered one of the main stumbling blocks for a sustained recovery of the domestic economy. Adding new jobs would provide investors reassurance that the ongoing rebound remains on track.

The ADP jobs report showing employers added 32,000 jobs in April was better than the 30,000 jobs economists had forecast would be added.

The ADP report is seen an early indicator of the government's closely watched monthly employment report, though there are often wide variations because the ADP only accounts for private-sector jobs.

The Labor Department is expected to report on Friday that the unemployment rate was unchanged at 9.7 percent last month as employers added 200,000 jobs.

Meanwhile, bond prices rose Wednesday. The yield on the benchmark 10-year Treasury note, which moves opposite its price, fell to 3.55 percent from 3.60 percent late Tuesday.

Gold and oil both fell.

Overseas, Britain's FTSE 100 fell 1.1 percent, Germany's DAX index dropped 0.7 percent, and France's CAC-40 fell 0.6 percent.