The Silicon Valley billionaire Peter Thiel has put the future of Gawker Media in doubt by secretly funding a successful lawsuit that threatens to undermine the media company’s finances.

To do it, Mr. Thiel, a co-founder of PayPal, adopted tactics from a strategy used by investment firms and others who are increasingly underwriting lawsuits in the hope of turning a profit on their outcomes. Over the last decade, the types of lawsuits that have attracted outside money range from product liability claims brought by consumers against manufacturers to lawsuits filed by one business against a competitor over commercial issues like copyright violation.

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“Many academics fully embrace third-party litigation funding as leveling the playing field,” said Nora Freeman Engstrom, a professor at Stanford Law School.

The precise nature of the relationship between Mr. Thiel and Mr. Bollea’s lawyer is unclear. However, legal experts like Ms. Engstrom that say lawyers who accept funds from people who are not parties to a case face certain obligations, like not disclosing confidential information obtained during a lawsuit to an investor or placing an investor’s interests ahead of those of a client.