On the Internet, people talk about everything, even their illnesses. Now, Wall Street is listening.

In the data age, a handful of companies are packaging conversations on Facebook, Twitter and online patient forums to sell to drugmakers, insurers and hospitals eager to understand how people manage their health in the real world.

One of them has started putting its data-excavating skills to use beyond the health-care industry and selling it to financial companies looking to gain an investment edge. Treato, based near Tel Aviv, sends fund managers weekly or monthly reports with analysis of online chatter that may yield early signals about a drug’s side effects or prescription patterns.

“If it’s proven you can actually make better investment decisions by using this, investors will flock to it,” said Les Funtleyder, portfolio manager for Esquared Asset Management. Funtleyder isn’t a client of Treato and he’s cautious about using such data for investing.

While others such as Saama Technologies Inc. and Signals Intelligence Group ply their trade of “social listening” to the health-care industry, closely held Treato is one of the few also putting its algorithms to work for the investment community, according to Brigham Hyde, vice president of data science at consulting firm Decision Resources Group.

The Web, which on Facebook and in chat rooms can convey a sense of seclusion, is emerging as a gold mine of personal data that aggregators can scoop up to find out anything ranging from shoe-shopping preferences to medical history -- and sell to marketers. The harvesting is raising privacy concerns.

‘Not Beyonce’

“Everyone knows what they put on the Internet is open, but most people think, ‘Nobody really cares about me, I’m not Beyonce,’” said Deborah Peel, founder of non-profit organization Patient Privacy Rights. “They don’t realize this is the biggest business in the digital world.”

When Ed Sikov was diagnosed with Parkinson’s disease, he joined PatientsLikeMe, an online discussion platform where people can track their conditions and share their experiences. It has more than 250,000 members and its forums cover 2,000 conditions. PatientsLikeMe sells the data it gathers to drugmakers listed on its website, including Abbott Laboratories and Bristol-Myers Squibb Co., making it a rival to Treato. Founder Ben Heywood didn’t rule out selling information to health investors in the future.

Using Treato