(ShareCast News) - Woodford Patient Capital Trust announced its unaudited half-yearly financial report for the period from 1 January to 30 June on Thursday, with net assets falling to £717.89m from £814.86m a year ago.The FTSE 250 firm's net asset value fell to 86.81p from 101.86p, while its share price at the same time dropped to 84.1p from 113.5p.Its board reported "good operational progress" among its holdings, saying a number of companies delivered strong returns although negative sentiment towards health care sector impacted returns.Two additional directors were appointed to the board during the period."The company experienced a challenging half-year period that reflected both a turbulent market for small-to-medium-sized quoted companies and the uncertainty that surrounded the EU referendum," said chairman Susan Searle."However, Neil and his team have constructed an impressive portfolio of companies about which they have deep knowledge and insight."Many of these companies have delivered extremely encouraging operational progress and the board remains excited about the investment opportunities that the company was formed to exploit with its diverse portfolio of disruptive businesses with high-growth potential," Searle said.Head of investment Neil Woodford said it had been a tough start to the year for financial markets and for the company, but "considerable progress" was made across much of the portfolio."Since the period end, there has been some meaningfully positive and noteworthy news from several companies in the portfolio - six of which make up 30% of the portfolio."These companies, which include Prothena, 4D Pharma and Immunocore, are indicative of the exciting progress being delivered by the portfolio as a whole and the high long-term growth potential that awaits us," he said.Woodford said he understands that some investors will be disappointed with the performance so far, but insisted it is "early days" for a strategy looking to exploit very long-term opportunities.He explained that the share prices of quoted early-stage businesses can be volatile, adding they may sell off in small volume for no fundamental reason."I see these events as opportunities because share prices can become detached from reality."As I have said before, not everything we invest in, small or large, will succeed and some will encounter problems," Woodford said.