ProShares Ultra S&P500 SSO ETF
The SSO is an ETF managed by ProShares, an investment fund manager. This ETF seeks a return of 200% of the return of the S&P500 index for a single day. (Note: compounding effects will make the multi-day return different.)
Compare this to ProShares UltraShort S&P500 SDS ETF.
ProShares' official page on the SSO: http://www.proshares.com/funds/sso.html
Ticker: SSO Intraday Ticker: SSO.IV CUSIP: 74347R107 Inception Date: 6/19/06 Expense Ratio: 0.95% NAV Calculation Time: 4:00 p.m. ET