A share/stock reaching 52 week high determines possibility of strong gains ahead. However, 52 week high stocks must be thoroughly analysed before investing i.e an investor must look into the fundamentals, financials (Balance sheet, P&L statement, cashflow etc.) technical charts and follow the market movement as well before investing in 52W high stocks. Investing in 52 week high stocks may sound like a potential opportunity. At the same time you must evaluate the risk associated with it as well. Only considering a day's movement of price change may not be a good investing factor.