The U.S. midterms are playing out against a controversial new scoreboard, as the nation votes in its first major elections since prediction markets went mainstream.

With hundreds of millions of dollars on the line, experts are warning that the proliferation of live odds into news coverage and on social media could sow confusion — and provide fodder for misinformation.

Concerns range from motivated actors taking extreme measures to sway markets, to voters overtrusting the odds and baselessly blaming fraud where election results differ.