As traders freaked out by this week's stock market rout ponder what lies ahead, UBS analyst Solita Marcelli remains bullish that U.S. stocks will continue their upward trend in the coming months. She said the brief spike in the Cboe Volatility Index (VIX) to multi-year highs earlier this week also provided traders with an opportunity to enter the market, especially for those on the sidelines. She noted that U.S. stocks typically return above average in the three, six and 12 months after Wall Street's fear index spikes. "We're going to have some volatility, but I think there's still some decent upside," Marcelli said.