The “alternative data” industry, which sells information such as app downloads and credit card purchases to investment groups, is failing to adequately erase personal details before sharing the material, according to several hedge funds.

The rapidly growing world of big data is seen as an increasingly attractive source of information for asset managers seeking a vital investment edge, with data providers selling everything from social media chatter and emailed receipts to federal lobbying data and even satellite images from space. But several hedge funds say some vendors are selling information that still contains sensitive personal information that could be used to identify individuals.

“The vendors claim to strip out all the personal information, but we occasionally find phone numbers, zip codes and so on,” said Matthew Granade, chief market intelligence officer at Steven Cohen’s Point72. “It’s a big enough deal that we have a couple of full-time tech people wash the data ourselves.”