Clinton's prospects in betting markets tumble on health concerns

NEW YORK (Reuters) - Online betting markets cut back Hillary Clinton's prospects of winning the Nov. 8 election after a video showed the Democratic presidential candidate stumbling and having difficulty walking as she was helped into a van at a Sept. 11 memorial, raising concerns about her health.

Her probability of victory fell 7 percentage points to 64 percent on Sunday, the biggest one-day drop since she accepted her party's nomination in late July, according to online predictions market PredictIt. Sunday's trading volume on PredictIt was also the largest in at least three months.

The sharpest plunge occurred immediately after the video, taken by a bystander, showed up on social media.

In a modest rebound on Monday, her prospects rose 1 percentage point on PredictIt, but trading volume was low as she canceled a planned trip to California for fundraising and other campaign events.

Her campaign disclosed that Clinton, 68, had been diagnosed with pneumonia on Friday after she complained of allergies and was seen coughing repeatedly in recent days.

The health problem was the latest blow to Clinton's White House bid at a time when Republican rival Donald Trump has erased most of her lead in national opinion polls and is competitive again in many battleground states where the election is likely to be decided.

Trump's prospects on PredictIt rose following news about Clinton's health incident, up 3 percentage points to 34 percent on Sunday, the highest end-of-the-day level since July 30.

On Monday, his probability remained unchanged despite his pledge to soon release detailed information about his health.

Paddy Power, one of Europe's biggest gambling companies, also showed Clinton's chances of winning falling to 65 percent from 73 percent in the past 24 hours.

Trump's probability of winning rose to about 40 percent from 33 percent overnight, Paddy Power said.

According to the latest polls by Reuters/Ipsos released on Saturday, Clinton had an 83 percent chance of winning the election by an average of 47 votes in the Electoral College, the body that ultimately selects the president.

Late last month, Reuters/Ipsos's States of the Nation poll estimated Clinton had a 95 percent chance of winning by an average of 108 electoral votes.

The Electoral College consists of 538 electors, apportioned by states' populations; a candidate must pick up a majority of at least 270 electoral votes to win the presidency.

(Reporting by Angela Moon; Editing by Jonathan Oatis)