(The opinions expressed here are those of the author, a

columnist for Reuters.)

By Jamie McGeever

ORLANDO, Florida, June 2 (Reuters) - Many of the biggest

winners from the current wave of AI mania lifting Wall Street to

new highs aren't the multi-trillion-dollar hyperscalers, but

small caps. The question now is whether that can last.

Microsoft ( MSFT ), Amazon ( AMZN ), Alphabet,

Nvidia ( NVDA ) and other AI behemoths atop the Nasdaq

and S&P 500 continue to grab headlines as valuations hit

ever more stratospheric heights, with investors also eagerly

anticipating trillion-dollar IPOs from Anthropic and OpenAI.

But amid all this, companies with market caps below $2

billion have undergone a stealth rally. The small-cap benchmark

Russell 2000 index is up 17% this year, outstripping the

S&P 500's 10% rise.

Of course, there have been a few notable exceptions. The

$700 billion cloud computing giant Oracle has seen its

market cap nearly double in under two months, while $300 billion

PC-maker Dell's has doubled in less than two weeks.

But in general, the smaller players have led this year,

primarily driven by two sectors, tech and energy. The small-cap

indices in these areas have outperformed their more heralded

megacap peers by some distance.

SMALL BUT MIGHTY

On the energy side, the S&P 500 subindex has gained

an impressive 27% so far this year, but the equivalent Russell

2000 index is up 34%. Since February 27, the day

before the Iran war started, the Russell 2000 energy index has

jumped 13%, while its S&P 500 counterpart has risen only 2%.

Many smaller companies are better set up to benefit from an

energy price spike than their larger peers. That's because a

higher proportion of their costs tends to be fixed, so a rise in

oil prices will more readily lead to increased cash flow. While

crude prices are off their highs, they are still 30-35%

higher than where they were on February 27.

The small-cap outperformance has been even more pronounced

in tech. The Russell 2000 tech index is up 45% this

year, compared with the S&P 500 tech index's 25% rise,

with much of this outperformance coming in the last two months.

Since U.S. equity markets bottomed on March 30, small-cap tech

stocks are up an eye-popping 70%, while the large-cap tech index

has increased a mere 45%.

What explains this? Small caps appear to be benefiting more

from the AI capex boom than many had bargained for.

Tech may only account for about 16% of the small-cap index -

compared with the 'Magnificent Seven's' near-40% share of the

S&P 500, but many of these smaller companies are considered part

of the physical "picks and shovels" segment of the AI buildout.

And the deluge of hyperscalers' capex spending - estimated

at roughly $800 billion this year - is flowing through the AI

ecosystem to areas where many of these players are active, such

as equipment, power, and AI testing.

In fact, shares in more than a dozen small-cap semiconductor

firms have risen over 100% this year, notes Keith Lerner, chief

investment officer at Truist Advisory Services.

"This underscores how strong and widespread that demand has

been," Lerner says. "As for whether it can continue ... upside

potential remains, particularly if the bull market stays intact

and the AI-driven earnings cycle continues to broaden out."

SMALL FIRMS, BIG RISKS

Small caps face plenty of challenges ahead, however.

For starters, companies with smaller balance sheets, weaker

credit ratings and lower market capitalizations are more exposed

to rising interest rates than bigger firms.

For now, the rise in Treasury yields across the maturity

curve since the Iran war started has been offset by rising

equity prices and shrinking credit spreads. Indeed, Goldman

Sachs' U.S. financial conditions index is at its lowest point in

over four years, largely due to booming equity markets.

But inflation is creeping higher, with headline annual rates

approaching 4%, meaning borrowing costs may keep heading north.

At some point, this should curtail the equity boom, tighten

financial conditions and put disproportionate pressure on

smaller companies with high debt loads.

Any pullback in the AI capex splurge could also be a double

whammy, hitting many small tech companies directly and via

slower overall growth.

And if there is a resolution to the Iran conflict, energy

prices could drop through year-end, erasing the boom smaller

energy firms have enjoyed.

Bank of America's fund-manager survey showed conviction in

the small-cap rally may be ebbing. A net 54% of respondents now

expect large-cap stocks to outperform small-cap stocks, the most

since June 2022.

Small caps are on a good run. How much stamina they have to

extend it remains an open question.

(The opinions expressed here are those of the author, a

columnist for Reuters)

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(By Jamie McGeever

Editing by Marguerita Choy)