This Element is an excerpt from The ETF Trend Following Playbook: Profiting from Trends in Bull or Bear Markets with Exchange Traded Funds (ISBN: 9780137029013) by Tom Lydon. Available in print and digital formats. Simple ways to avoid investment bubbles, capture profits from markets headed up, and get out in time! Buying and selling according to investment trends is so simple that any investor can do it. The rules are as follows: 1. Buy when a position moves above the 200-day moving average. 2. Sell when a position moves below the 200-day moving average. 3. Leave your emotions at home.