There’s no denying that US stock market had a difficult first quarter, especially following such an incredible 2013, and setbacks have been blamed on everything from Russian action in Ukraine to the weather. Leon G. Cooperman, Steven G. Einhorn, and Andrew Parlin of Omega Advisors Inc. argue in a letter to investors that the reality is simply that investors are becoming complacent and piling into overcrowded positions without regard to stock fundamentals. Even so, they think that the last quarter will prove to be a period of consolidation and that the bull market has much further to run, according to the…