Investors should position themselves for a market rally as worries over President Donald Trump's tax reform chances are overstated, according to a top Wall Street firm.

JPMorgan derivatives strategist Shawn Quigg told investors to buy call options on companies that will benefit the most from tax reform.

"We think the most significant near-term upside catalyst for equities is still ahead – passage of the US Tax Bill. Our analysis indicates the market is significantly underestimating the probability of tax reform passage," Quigg wrote Monday in a note entitled "Top Tax Outperformers for Upside Call Buying." "We think the potential passage of tax reform could provide 5 percent near-term upside to the S&P 500. However, the potential upside could be significantly higher for those high-tax stocks poised to outperform in a more tax-friendly regime."

As a result, the strategist recommended investors buy call options in Concho Resources, Hilton Worldwide, Southwest Airlines, ConocoPhillips, Marathon Petroleum, E-Trade, Regions Financial and CF Industries. A call option is contract to buy shares in the future at a set price and generally a bullish bet.

JPMorgan's research team has overweight ratings on Concho Resources, Hilton Worldwide, Southwest Airlines, ConocoPhillips and Marathon Petroleum shares.

The firm has neutral ratings on Regions Financial and CF Industries. It does not officially cover E-Trade shares.