Eventually, they could end up on your roof, beaming trading data across the sky: Lasers, originally developed by the military, that are now being co-opted by high-frequency traders looking for even faster ways to do business.

These beams are faster than fiber optics, faster than microwaves, faster even then the millimeter-waves that most high-speed traders use today. They’re the last resort for companies trying to out-trade their competitors by slivers of milliseconds—a technical competition that The Wall Street Journal…  Read full article.