What are the best performing stocks over the past year? Go to finance.yahoo.com and select the “Stock Screener” link. You will see a “Performance” category and a pull-down menu labeled “1 Yr Stock Perf.” Select “Up more than 200%” and “Find Stocks.” How many stocks have increased more than 200% over the past year? Now go back and select “Down more than 90%.” How many stocks have dropped more than 90% in value over the past year? What does this say about market efficiency?