Self-managed investment trust Personal Assets Trust outperformed its benchmark index this year.The FTSE 250 group posted a 4.8% total return on net asset value per share in the year to 30 April compared with a 3.9% total return from the FTSE All-Share Index.The trust said it retained a high level of liquidity in the period, which amounted to 59.9% at the end of April, including 22.1% in UK cash and cash equivalents and 37.8% in various classes of non-equity risk assets."We kept pace with their modest rise as equities held on to their strong gains of recent years, buoyed on an ever-rising tide of liquidity," said the trust's Investment Adviser Sebastian Lyon.On Friday, Personal Assets Trust shares closed down 0.34% to 35,050.00p.