Between the upcoming presidential election and concerns about Deutsche Bank's solvency, investors have plenty of reasons to hit the sell button. However, one of Wall Street's biggest bull investors says that would be a mistake.

Tom Lee, Fundstrat Global Advisors' Head of Research, says he is "absolutely" buying any dip in stocks. Heading into the fourth quarter, Lee expects the to jump another 7 percent before the end of the year.

"People are worried about a lot of things, like the elections and obviously…Deutsche Bank. But we have to remember, investors are basically are negative, so we've got sentiment working in our favor," said Lee on "Fast Money" this week.

Just this week alone, 16 different stocks in the S&P 500 hit new 52-week highs, names that included Amazon, Caterpillar and eBay.

By Lee's work, the overwhelming negative sentiment in the market could actually act as a positive catalyst for stocks. According to the analyst, the S&P 500 has already surpassed the average sell side strategist price target. Since 1999, each time this phenomenon has occurred, stocks have rallied 95 percent of the time over the next 12 months.

Lee also noted the pessimistic market sentiment is currently shared by both institutional and retail investors alike. A recent investment survey showed that retail investors are as bearish now as they were post Brexit — this despite the fact that the S&P is just percentage points away from making all-time highs.

Still, in spite of his bullishness, Lee is warily eyeing shares of Deutsche Bank, the German banking giant that was buffeted by fears that evoked bad memories of 2008's financial crisis.

"If Deutsche Bank leads to a true ceasing of credit markets and credit access and liquidity then that itself, because of the effect it would have on the underlying economy, it could drive us into a recession and that would be bearish," Lee said.