A Google engineer has been arrested for allegedly using his employer's secret search trend data to win $1.2mn on Polymarket as landmark case tests whether prediction markets are subject to the same rules as Wall Street.

A Google staffer fraudulently made more than $1 million by using inside information to place Polymarket bets on what users were searching for on Google, authorities say.

He's been charged with commodities fraud, wire fraud and money laundering.