* Market needs substantial catalyst to rise further - analyst * Nikkei sluggish as weak yen trend pauses after BOJ * Canon rises on share buyback plan By Ayai Tomisawa TOKYO, Feb 19 (Reuters) - Japan's Nikkei share average fell on Wednesday morning, retreating from a 2 1/2-week high hit the previous day, as investors took profits on banks and exporters when the weak yen trend paused. The Nikkei shed 0.7 percent to 14,738.69 in mid-morning trade after rising 3.1 percent at 14,843.24 on Tuesday, the highest close since Jan. 31. It was the biggest daily percentage gain since early August. Mitsubishi UFJ Financial Group dropped 1.4 percent, Sumitomo Mitsui Financial Group shed 1.6 percent and Mizuho Financial Group fell 1.8 percent. On Tuesday, they all rose nearly 5 percent after the Bank Of Japan decided to extend three special loan facilities by a year from their scheduled expiry at the end of March and double the size of funds available to banks. Analysts said that the market took heart from the BOJ announcement, but that effect will fizzle soon. The market needs more drivers for the benchmark to top its psychological resistance line at 15,000 and rise further, they added. "Investors have either based their investment decisions on U.S. economic data or expectations that the BOJ will ease further," said Norihiro Fujito, senior investment strategist at Mitsubishi UFJ Morgan Stanley Securities. "The market has relied too much on the BOJ. We need a substantial reason to chase the market higher such as concrete growth plan from our leader." Last June, Prime Minister Shinzo Abe disappointed the market with his detail-lacking 'third arrow of Abenomics', or the plan to pull the country out of its long slump. "If he does not flesh out his 'third arrow' by the end of this fiscal year, it would be disappointing," Fujito said. The Topix shed 0.2 percent to 1,221.50. Exporters were weaker after enjoying rallies on Tuesday, with Honda Motor Co falling 1.6 percent and Sony Corp shedding 1.9 percent. But Canon Inc bucked the weakness, rising 2.5 percent after the company said it would buy up to 18 million of its own shares worth 50 billion yen, or 1.6 percent of its outstanding shares. Canon was the fifth most-traded stock by turnover. The JPX-Nikkei Index 400, an index launched this year comprised of firms with high return on equity and strong corporate governance, dropped 0.1 percent to 11,051.95.