Portfolio managers at Scottish Mortgage Investment Trust will have enjoyed their Hogmanay after the trust's net asset value bounced 8% higher in the fourth quarter of 2009.Net asset value (NAV) per share, after deducting borrowings at fair value, rose to 609.6p at the end of 2009 from 567.8p at the end of September. Over the same period, NAV per share after deducting borrowings at par improved to 627.1p from 589.4p.The 8% boost to NAV compared to a 3.6% increase in total returns by the combined performance of the FTSE All-Share and FTSE World (excluding the UK) indices, the benchmark against which the company measures its investment performance.Total borrowings at fair value eased to £346.5m from £362.1m at the end of September, while the 'at par' figure narrowed to £299.8m from £303.4m.In the final quarter of 2009 the company bought back 3.445m shares at a cost of £18.0m, thus improving NAV per share by 0.17%.Tradign activity saw the company's top twenty investments by value change its composition, with Baidu and New Oriental Education & Technology joining the list and China Mobile, Porsche and Vestas Windsystems leaving it.