The Vanguard S&P 500 (VOO) ETF has undergone a split just once in its lifetime. It occurred on Oct. 24, 2013, when its share price was falling. The company conducted a 1-for-2 reverse split, meaning it combined every two shares held by its investors into a single one. The reverse split reduced the number of shares in circulation and doubled the ETF's price. It also reduced the spread of the difference between the buying and selling price of shares for investors.