(Sharecast News) - International Public Partnerships issued its half-year results for the six months ended 30 June on Thursday, reporting continued robust portfolio performance with a strong dividend yield, and further growth in its net asset value driven by active asset management and selective, accretive investments and commitments totalling £50.5m.The FTSE 250 firm said its net asset value grew to £2.1bn during the period, from £2bn at the end of December.Its net asset value per share was 146.3p, compared to 145p on 31 December, with the interim dividend increasing to 3.5p per share from 3.41p per share a year ago.The board said IFRS profit before tax stood at £65.9m for the half-year, up from £57.1m for the first half of last year.It explained that it saw enhanced inflation-linkage, with a projected increase in return of 0.81% per annum for each 1% per annum increase in inflation.The company was targeting 2018 and 2019 full-year dividends of 7p and 7.18p per share, respectively.Cash dividend cover for 2018 stood at 1.2x.On the operational front, International PPL said the strength of its investment adviser's active asset management and portfolio risk management approach was demonstrated by the "prompt resolution" of Carillion-related matters, which impacted a "small number" of projects, at no material financial impact to the firm or its public-sector clients.Post-period end, the company had successfully renewed and extended its corporate debt facility to £400m on improved terms.It said it had a "sustained" track record of delivering "stable and growing" shareholder returns, with two-year forward dividend guidance for 2018 and 2019 projecting annual dividend increases of around 2.5%.The company's total shareholder return since IPO was now 148.6%, for an average compound annual growth rate of 8.1% since IPO in 2006, in line with its long-term returns target of between 8% and 9%."As a result of the ongoing robust portfolio performance in a period in which we continued to maintain full asset availability for our end-users, I am pleased to report sustained delivery of long-term inflation-linked returns to our shareholders," said International PPL chairman Rupert Dorey."The market for the type of assets in which the company invests remains buoyant and we remain confident in our ability to realise a long-term pipeline of harder-to-access opportunities that meet our established risk-return profile."