Long-time Lone Pine managing director Paul Eisenstein is starting his own fintech-focused investing firm

• Paul Eisenstein has been an analyst for Lone Pine for 13 years, rising to become a managing director at the Greenwich, Connecticut-based fund.
• The firm's third-quarter letter said that he will leave at the end of the year to begin investing personally in innovation in financial services, "either with his own capital alone or with outside capital as well."
• It is unclear if Eisenstein plans to start his own fund or run a family office-like structure. Lone Pine's letter stated he will primarily focus on financial services.
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After 13 years of making money for Stephen Mandel Jr., Paul Eisenstein is setting out on his own.

The long-time analyst for Lone Pine Capital will leave the firm at the end of the year, according to the firm's third-quarter letter, and will start investing in "innovation," mostly in financial services, which he covered at Lone Pine. The letter said that it may be solely his own money, or "with outside capital as well."

"Paul has been an important contributor to our results in financial services and is a highly-respected colleague," the letter reads.

"We plan to stay in close touch and hope that there will be areas of investment collaboration in the future."

Lone Pine declined to comment on if the firm plans to back his new venture. Eisenstein did not respond to requests for comment. According to his LinkedIn profile, Eisenstein has only worked for Lone Pine in his professional career.

The letter did not specify what type of investment vehicle Eisenstein would run. While Lone Pine is opening itself up more to private-market investments, it still caps the total amount of private investments at 5% of its funds' assets.

Similar to fellow Tiger Cubs like Maverick and Viking Global Investors, Lone Pine has had many alums start up their own funds.

David Stemerman ran Conatus Capital Management for 10 years before closing in 2017 so he could run unsuccessfully for governor in Connecticut, and former managing director Brian Eizenstat started Dilation Capital this year.

Read more: Lone Pine Capital's latest client letter argues value investing is going extinct - and says downtrodden stocks are cheap for a reason