Wal-Mart has announced it will raise its minimum wage to $9 an hour in April, and $10 next year, in a move that will impact about half a million low-wage workers. The increase falls far short of the $15-an-hour living wage demanded by workers who have launched historic strikes against Wal-Mart — and reported retaliation from the company for joining the protests. A 2012 analysis found the six heirs to the Wal-Mart fortune have as much wealth as the bottom 40 percent of the United States combined.