By Michael Sincere Veteran trader Steve Burns prepares for a 50% decline and exposes the 3 'deadly stock-market sins' destroying portfolios today When the SPDR S&P 500 ETF Trust (SPY) closes below its 200-day moving average on a daily basis, go to cash. Steve Burns is the founder of NewTraderU.com, a stock-market-trading education platform he launched in 2011, and the author of more than 25 books on markets, trading psychology and risk management.