Michael Dell has sold 10 million shares of his namesake company for nearly $297 million, according to a filing made today with the Securities and Exchange Commission. However, he still owns about 277.9 million shares of Dell ( DELL). As of April 30, he controlled 11.6% of total shares outstanding. Dell sold the 10 million shares between May 22 and May 27, at prices ranging from $29.56 and $30.01. Including the latest sale, Dell, his wife and his children's trust have collectively sold off 32 million shares of their company stock since last November , coinciding with a slew of hefty stock sales by other high-ranking Dell execs. While Michael Dell's sales have historically foreshadowed a rise in the stock, many observers on Wall Street think Dell may not have much room for upside at current levels. Dell's stock has already risen 12.2% year to date through Tuesday's close, outperforming the broader market. The S&P rose only 8.1% in the same period.