On September 19, PPL (PPL) stock had an implied volatility of 17%—marginally higher than its 15-day average. In comparison, the volatility in the Utilities Select Sector SPDR ETF (XLU) was ~13%. The implied volatility represents investors’ nervousness. Increased volatility is usually associated with a fall in stock prices. Recently, the SPDR S&P 500’s implied volatility was 8%.