The software and computer services sector was trading higher on Wednesday with engineering software firm AVEVA lifting the category after an upgrade by UBS.Shares in the FTSE 250 firm were up 7.2% at 2,276p before the close of trade after analysts at the Swiss bank raised their rating from 'neutral' to 'buy', saying that after a period of underperformance the stock now looks "attractive".AVEVA, which operates in the plant and marine industries, saw its share price sink sharply in November 2013 after it said that growth in the Enterprise Solutions business had been slower than expected due to two "company-specific external factors". To make matters worse, there were a number of profit warnings across the oil services sector which dampened sentiment.UBS said that valuation has long been its major reservation in relation to AVEVA, but the stock looks like "better value now". Meanwhile, the company is also on the bank's "M&A WatchList".AIM-listed Coms, the telecoms and IT services provider, was up nearly 11% as investors continued to rise on Monday's announcement of five contract wins."We anticipate 2014 will be a transformational year for Coms and we look forward to announcing more contract wins as the year progresses," said Chief Executive Officer Dave Breith on Monday.Castleton Technology was also a high riser in the software sector, rising by over 15% after saying yesterday that an investment group associated with its CEO and another director had purchased 10m shares in the company, spending over £6m. MXC Capital now owns a 25.6% stake in the company, equal to nearly 160m shares.Top performing sectors so far todaySoftware & Computer Services 1,175.48 +1.14%Real Estate Investment & Services 2,764.30 +0.88%Technology Hardware & Equipment 1,232.81 +0.73%Banks 4,967.94 +0.50%Health Care Equipment & Services 4,887.81 +0.45%Bottom performing sectors so far todayGas, Water & Multiutilities 5,492.98 -1.72%Industrial Metals & Mining 1,332.07 -1.60%Tobacco 35,395.04 -1.31%Food Producers & Processors 7,154.52 -1.30%Electricity 9,038.12 -1.05%BC