(ShareCast News) - Investment trust Law Debenture's net asset value total return for the half year missed its benchmark due to Brexit, but the company maintained its interim dividend.For the six months ended 30 June, net asset value total return was 1.5%, compared to a total return of 4.3% for the FTSE actuaries all-share index. Law Debenture said it underperformed due to movement in the value of its long term debt because of low gilt yields.Net revenue per share fell 2.4% to 10.49p.The interim dividend remained steady at 5.2p, the same as last year. The current expectation is that the final dividend will be maintained.The company said it had been a volatile period for equity markets, with macro-economic issues driving large swings in equity values, exacerbated by the disruption caused in the immediate aftermath of the UK's decision to leave the European Union on the 23 June.The AIM listed company's portfolio benefitted from positive returns in sectors with their profits predominantly overseas in US dollars, such as mining and oil. The company's top performers were Anglo American, Royal Dutch Shell, Glencore, Weir and BP.The company has a relative mid-weight presence in British mid-cap and small-cap companies, which are more reliant on the UK economy for their turnover and profit. They suffered price falls immediately after Brexit as sterling tumbled. The worst performers were Interserve, IP Group, International Consolidated Airlines, Provident Financial and Marshalls. The company believes their share price will eventually recover.Revenue, net of sales cost, which represents legal costs recharged to clients, fell by 2.4%, administration costs decreased by 1.6% and profit before tax also fell by 2.3%.Law Debenture said: "Our relative performance, compared to peers in the global sector and the benchmark, has suffered badly since Brexit, largely because of our exposure to sterling. However, so long as the companies we are invested in have competitive products, good management teams, undemanding valuations, low debt levels and cash generative capability, they ought to weather this storm and should be well placed to deal with the post-Brexit economic turbulence."In view of elevated economic uncertainty, we have been net sellers in the portfolio since the period end and are taking a cautious approach in our investments".Shares in Law Debenture fell 0.85% to 494.50p at 1549 BST.