Markets are expected to open slightly higher on Friday, building on the previous day's gains which sent the FTSE 100 to its highest level in over a month.City sources predict the FTSE 100 will open up 11 points from yesterday's close of 6,543. The last time the index had finished above that level was on June 4th. Both the S&P 500 and Dow Jones indices finished at record highs on Thursday night, while the Nasdaq closed at its highest level in 13 years, as Wall Street reacted to dovish comments made by Federal Reserve Chairman Ben Bernanke the night before.Bernanke caught the attention of investors on Wednesday night as the Fed chief looked to reassure markets that short-term interest rates wouldn't be rising anytime soon, even if the unemployment rate falls dramatically. "It may be well sometime after we hit 6.5% before rates reach any significant level," he said.Stocks to watchOxford Instruments, which provides technology for research, had a slow start to the year, according to a trading update for April 1st to date. The company said performance in the first two months of the year was down in comparison to a strong prior year. However, sales and profits picked up in the third month of the quarter, ahead of the same period last year. British Gas owner Centrica has sealed a cash deal to buy Bounce Energy, a Texas-based electricity retailer with an innovative digital strategy. Centrica's North American subsidiary, Direct Energy, will pay $46m (£30m) cash and some extra working capital to acquire the new business.Experian said it had healthy revenue growth in the first quarter, outpacing economic growth in its main markets. The credit checking company said total revenue increased 7.0% in the three months to June 30th at constant exchange rates. "Organic" growth rose at the same rate.BC