Shares of SemiLEDs Corp. /zigman2/quotes/208055520/composite LEDS +2.12% shot up 33% on heavy volume, enough to pace all the Nasdaq-listed gainers, after the Taiwan-based maker of light-emitting diode chips disclosed it received an offer to buy nearly one-fifth of the outstanding shares. Trading volume swelled to 12.8 million shares, compared with the full-day average of about 31,000 shares. The company said in a filing with the Securities and Exchange Commission late Tuesday that an individual investor living in China, Xian Chang Ma, offered to buy 680,000 shares at $3.00 each. The $2.04 million investment would represent about 19% of the shares outstanding. SemiLEDs board if directors will decide whether to pursue the offer on or before Aug. 30 at 5 p.m. Eastern. If the sale closes, the board is expected to nominate Ma, how is currently chairman and chief executive of Shandong Tengjunxiang Biotechnology Co. Ltd., to its board. The stock has gained 9.3% year to date, while the PHLX Semiconductor Index [s; sox] has soared 30.9% and the S&P 500 /zigman2/quotes/210599714/realtime SPX -0.39% has advanced 16.7%.