One year ago today, the markets had bled out 34% in just 24 trading days, including one of the fastest bear market drops ever, bottoming on March 23, 2020.

But since that trough, the rebound has been remarkable—and historic. The S&P 500 is up 76% as of March 22's close, while the tech-heavy Nasdaq Composite is up a massive 95%. The Dow, meanwhile, has gained 76%. (Stocks took a tumble on March 23, however, with each index down at least 0.76%.)

Not only are those numbers staggering, but they also represent the strongest one-year rebound from a bear market ever (even beating out 2009's big 68.6% one year rally), per an LPL Financial research report out March 22.

But after such a plentiful year for investors, where can the stock market go from here?

Reasons for “further upside”

Those like Chris Zaccarelli, chief investment officer at Independent Advisor Alliance, point out the obvious: "I think it's hard to replicate the speed of the move that we've just had, so I think our expectations are quite a bit tempered" for 2021, he tells Fortune.

But Zaccarelli notes he's seeing a lot of tailwinds for stocks, "whether it's the fiscal stimulus, the Federal Reserve providing lots of monetary accommodation and a pledge to keep short term interest rates low for an extended number of years," he says. "We really don't see anything to derail the bull market."

Indeed, others like UBS Global Wealth Management’s chief investment officer Mark Haefele agree that "despite the rally and the fact that the pandemic is still ongoing," he notes, "we see reasons for further upside in risk assets," Haefele wrote in a March 23 note.

What's more, based on historical data, things often look good for the second year of a fresh bull market. The LPL report notes that since World War II, "there have been six other bear-market declines of at least 30%, and in every single case the S&P 500 was up firmly the first year of a new bull market," while the "gains continued in year two, as stocks were also up the second year of a new bull market every single time—up a solid 16.9% on average," the LPL strategists wrote.

However, it's likely not going to be a straight shot up. Pullbacks are also common in the second year of a new bull market, the LPL strategists note, with an average 10.2% selloff.

Currently, worries of rising inflation, a sudden change in bond yields or the Fed's accommodative stance, and possible big tax policy changes are weighing on some investors' minds. Meanwhile, many on the Street have been leaning into the rotation trade, looking outside of the tech and growth stocks that were the strongest rebounders during this bull rally and focusing on value and cyclical stocks.

Ultimately, "We don't see it in a straight line," Independent Advisor Alliance's Zaccarelli argues of the trajectory of stocks this year, "but we're not of the camp that the market is so overvalued that it's due for a crash or a bear market. I think we have some room to run here."