By Ellen Chang Short sellers reversed course and sold $19 billion of shorts in September. The volatility in the stock market rose in September, resulting in short sellers selling $19 billion of new shorts in eight trading days during the second half of the month. The Dow ended with a nearly 500-point drop on Sept. 23, a decline of 4% and below the 30,000 mark as recession concerns rose with the Federal Reserve continuing its hawkish stance. Equities extended declines into a fourth consecutive session while stocks globally dipped to the lowest levels in two years. Investors have been retreating…