[jackcosgrove]

I have heard that quant trading firms build software systems that have sub millisecond response times to data feeds.

Are the signals coming though these data feeds (reports by government agencies, news events, corporate filings) really occurring that fast? Or do the systems simply need to have low latency for responding to infrequent events (infrequent relative to the response time)? Or are the trading systems trading against each other in a kind of feedback loop long after a signal comes in over the wire?