The blink of an eye lasts 300 to 400 milliseconds. And the last time you blinked, billions of dollars were made or lost through high-frequency trading - the lightning-speed, mathematics-driven, computer-based buying and selling of huge blocks of securities.
It's the way the bulk of trading is done nowadays in the United States. It's going to take over stock exchanges around the world and will leave retail investors like you and me flailing in its wake.
More stock exchanges may be providing 'real-time' prices to various free website services such as Google and Yahoo Finance, but we don't stand a chance against speed trading measured in milliseconds.
Our traditional image of securities trading is hectic activity on the trading floor, with brokers yelling into phones, traders waving paper order slips and talking heads opining on firms' results and the impact on their stock prices - facts and figures that ordinary investors can understand and act on.
That relatively low-tech scenario is receding from today's hi-tech reality. Financial markets are increasingly driven by the arcane mathematics programmed into supercomputers, and the market movers are high-frequency traders - armies of mathematicians who decide to buy or sell securities in milliseconds.
Their decisions are based on the short-term statistical behaviour of a company's stock price regardless of that firm's fundamentals or prospects. Their goal is not to realise a healthy gain in the long term - a year, a month or even a day - but simply a cent or two per share in each transaction.