This bull market could be one for the ages if stocks keep going up.
The S&P 500 needs to climb just 6.4 percent from its current level for this bull market to become the greatest of all time, according to Leuthold Group, a firm long known for its market stat crunching on Wall Street.
Leuthold's chief investment officer, Doug Ramsey, said in a note entitled, "Year of the G.O.A.T.?" to clients that he thinks this bull market can surpass the one from the 1990s.
The chart below illustrates the cumulative S&P 500 gains from every bull market since World War II:
Source: Leuthold Group
"If the S&P 500 notches a close above 2,717, this bull market will become the Greatest (postwar) cyclical bull Of All Time— eclipsing even the 1990-1998 gain of +302%. It's already been a good year for G.O.A.T.'s, with Tom Brady, Roger Federer, and Floyd Mayweather all cementing their claims. With the S&P 500 less than 7% away, why not?" Ramsey wrote.
The current bull market became the second best of all time earlier this year. The S&P 500 has risen approximately 14 percent in 2017, led by strong gains in technology and health-care shares.
But Ramsey's is not the only strategist on Wall Street who's recently called for more upside to this bull market.
Jonathan Golub, a strategist at Credit Suisse, initiated his year-end 2018 target for the S&P 500 at 2,875, implying 13 percent upside from the index's current levels.
"Our market views are predicated on a supportive economic backdrop, with benign recessionary risks and a pickup in near-term indicators," Golub said in a note Monday.
The stock market could also see further gains if the Trump administration can move forward with tax reform. Renewed hope for tax reform has recently lifted the S&P 500, along with the Dow Jones industrial average and Nasdaq composite, to record highs.