By Tim McLaughlin

BOSTON (Reuters) - The manager of Fidelity's OTC Portfolio, a top investor in Tesla Motors Inc and SolarCity Corp, gave the electric automaker's strategies a vote of confidence in his most recent commentary to fund shareholders.

"We are fans not just of Tesla products but of the concepts underpinning the firm and potential future partnerships ahead of it," Fidelity Securities Fund Over the Counter Portfolio manager Gavin Baker said in his quarterly commentary for investors.

"We foresee fruitful synergies between Tesla and any company in search of superior battery technology, and we modestly increased our position this quarter."

The commentary, posted on Wednesday on Fidelity's website, comes as Tesla and SolarCity Corp are in the final stages of putting together an estimated $2.8 billion merger. Both companies count billionaire Elon Musk as a major shareholder..

Musk, the chairman and chief executive of Tesla, said on July 20 that he is looking to create a "smoothly integrated and beautiful solar-roof-with-battery product."

At the end of May, the Fidelity OTC portfolio was the second largest mutual fund investor in Tesla with 3.14 million shares. Fidelity's Contrafund, run by Will Danoff, was No. 1 among mutual funds with 5.5 million shares.

Fidelity funds combined are the second-largest investor in Tesla, holding about 11 percent of shares. Musk is the largest with about 20 percent, according to Thomson Reuters data.

Baker's OTC Portfolio is the largest mutual fund investor in SolarCity, owning about 9 percent of its shares at the end of May. Musk owns about 23 percent, according to Thomson Reuters data.

(Reporting By Tim McLaughlin; Editing by Tom Brown)