What a difference a month makes. April started out ugly for stocks and, well, took a pretty incredible turn. We might be saying the same -- for better or worse -- at the end of May, too.

The market took a nosedive only a few days into April after the harsh reality of the Trump tariffs took hold. Then, big-time backtracking by the administration -- a tariff pause and promises of trade talks -- gave Wall Street what it needed to pull itself together.

Stocks came roaring back, finishing April and starting May with a winning streak. On Monday, though, things were looking not so great again: the S&P 500 ended lower, snapping its nine-day winning streak. The Dow Jones Industrial Average and Nasdaq Composite closed down, too.

So a natural question: Is this a bear market rally or the start of a genuine new bull market?

Let's talk through it with experts.

There are certainly reasons for optimism.

As first-quarter reporting season carries on, results haven't all been sunny, but generally have held up a lot better than many feared -- S&P 500 2025 earnings estimates overall haven't come down substantially.

And ditto for economic data, despite all the hand-wringing about a recession.

Strategist Jordi Visser, 22V's head of AI Macro Nexus Research, thinks what we're seeing a new bull market.

Yes, it is possible, because of all the worry in the market right now, that there will be another leg down ahead -- but it won't last, he says.

There's too much broad-based momentum across sectors, and the sentiment is far out of proportion to the facts.

"Jobless claims and credit spreads show no signs of stress, yet sentiment remains at historically bearish levels," he notes. "This is a classic example of investors violating Bayesian principles -- refusing to update their views in light of new information."

That's true, although investors may have good reason to be slow about changing their minds.

Tom Essaye, president of Seven Report, points out that that there are tariffs that weren't in place at the start of the year. Unless the White House simply does away with all of them, virtually all the positives from the backtracking are already priced into the market.

Besides, the tariffs haven't been in place long enough for the fallout to be reflected in economic data and earnings reports. The second quarter and beyond is when the impact of tariffs will hit, he writes. In other words, the risk to both the economy and earnings growth is headed in one direction -- south.

"Bottom line, obviously we've enjoyed the rally and it is true that the actual events of the past month were not as bad as feared in early April, " Essaye concludes. "But not as bad as feared is not good, either, and I think the price action is implying the fundamentals are a bit better than they are in reality."

The upshot: Essaye thinks the S&P 500 will hover between 5,100 and 5,500, and he is sticking with defensive sectors.

On the technical side, Renaissance Macro's Jeff deGraaf believes the S&P 500 will face resistance around 5,740.

"That's not to say we won't overshoot, especially given sentiment, but this is where the burden of proof shifts back on the bulls," writes deGraaf, who is chairman and head of technical research.

"Recent tightening of credit spreads is constructive support," he said, "but we want to see a momentum thrust develop to suggest sustainable upside (not seeing by our metrics)."

Ned Davis, of Ned Davis Research, can make the argument either way -- bear market rally or new bull market.

Considering the market ended last year in a bit of a valuation-and-sentiment bubble, it might be hard to return -- and stay -- at those levels. Still, stocks had been oversold and strong breadth in the rally is a positive.

Then, what tip the scale for bear rally or new bull market?

The "fundamental key is likely whether we go into recession," Davis says.

Davis, by the way, thinks the economy already is in recession. There's just no hard data yet to confirm his theory.

If this is a new bull market, it could be crushed by Trump with a single social media post, like his one about movie tariffs that pulled down markets on Monday. What Truth Social gives, Truth Social can take away.

Ultimately, there is a scenario for a new bull market: Tariff deals are struck and some kind of GOP-supported tax package moves front and center.

Those major cuts to S&P 500 full-year earnings that seemed so necessary only a few weeks ago don't have to happen, and economic growth edges downward but doesn't fall off a cliff.

Then again, maybe not. Maybe tariff deals take a long time, the Republicans can't agree on tax cuts, and the economy tanks.

It's just a guessing game. Only time will tell.