BOSTON, Oct 3 (Reuters) - Hedge fund Highfields Capital Management is shutting down amid a period of lackluster returns and as its founder said he needs a change after two decades of managing money for prominent clients including Harvard University. Jonathon Jacobson told investors on Wednesday that he plans to convert the roughly $12 billion Boston-based firm into a family office and acknowledged that results in the “last few years” have fallen short of his expectations. Highfields has lost a little more than 1 percent this year and was up just slightly in 2017.