Not long ago, most investors had to wait until companies reported quarterly earnings to get a sense of how they were performing. Today, the ubiquity of data collection and the Internet of Things, coupled with advances in computing and machine learning, means early insights are that much closer and easier to access.

A hedge fund no longer has to send scouts to retail stores for a headcount of shoppers; instead satellite photos of cars in mall parking lots are analyzed at scale. Bots comb through millions of emailed receipts to harvest insights on shopping trends.

For years, so-called alternative data was the purview of a small fringe of hardcore believers, not the mainstream of investing. The creative, sometimes quirky strategies took traditional investors aback and were often of interest more for idle chatter than actual portfolios. But more recently, alternative data has matured. Recent investments by heavyweights like J.P. Morgan Chase and Goldman Sachs have lent an institutional backing. Bloomberg announced recently that it would sell alternative datasets through its terminal.

Nowhere is this more apparent than at the recent Quandl Data Conference in Manhattan. Now in its third year, the event brings together data providers and data seekers for talks around strategy, technical infrastructure and legal issues that arise when alternative data meets compliance. Founded in Toronto in 2012, Quandl makes a business out of finding and vetting previously unknown datasets and ferreting out useful and actionable insights. Broadly defined, alternative data is anything outside of the traditional financial statements and fundamental insights used by investors.

Some practitioners argue that investors have always used "alternative" data for prediction — Babylonians would supposedly use the water level of the Euphrates River to forecast what crops would do well in a given year. Contemporary alternative data practitioners use more than water levels. Sophisticated data gathering, cleaning and analysis has exploded in the past years, and there are over 400 alternative data providers out there, according to AlternativeData.org, a site run by YipitData, one of those providers.

Still, it's the early days.

"We're on the second batter of the second inning," said Adena Friedman, president and chief executive of Nasdaq. Further evidence that alternative data is itself becoming not so alternative: Quandl itself was purchased last December by Nasdaq.