Knight Capital (NYSE:KCG) has released its quarterly earnings, and in this video, Motley Fool financial analyst Matt Koppenheffer discusses the company's painful drop in tangible book value over the past couple of years. He highlights the one major error that the company made that cost it dearly and brought it very near bankruptcy, and he sees it as a healthy positive for society that it was the private market, not a government bailout, that brought the company back from the brink.