(The opinions expressed here are those of the authors.)

By Anna Szymanski

July 31 (Reuters) - Every Friday, Reuters Open Interest

(ROI) distills the financial week into five key charts,

spotlighting the major trends, surprises and overlooked moves

that defined the past five days.

1. COST OF CREDIBILITY

JAMIE MCGEEVER, ROI Markets Columnist: The 30-year Treasury

yield surged above 5.20% on Wednesday, the highest level in

nearly two decades. While yields have been elevated for weeks,

the latest move came in the wake of Federal Reserve Chair Kevin

Warsh's rather confusing post-meeting press conference on

Wednesday - suggesting his honeymoon is definitely over.

Markets seemed to be bothered less by the central bank's

actual decision - it kept rates unchanged - than by the Fed

chair's convoluted language, which raised questions about

whether the Fed will be willing to take the necessary actions to

bring inflation back to its 2% target.

No Fed Chair can allow that perception to take ​root,

especially not one who took office under a cloud of suspicion

about his independence from a White House that has explicitly

called for more dovish policy.

2. CHIP CHOKE

ANNA SZYMANSKI, ROI Editor-in-Charge: South Korea's chip

stocks had a volatile week to end a rough month. SK Hynix and

Samsung Electronics may have gotten a bounce on Friday - after

Microsoft and Amazon helped calm AI capex spending fears - but

they are still more than 40% and 25% below their June highs,

respectively.

This comes as the two tech giants released second-quarter

earnings that were extraordinary - just not extraordinary

enough. SK Hynix generated a sixfold rise in profit, but still

missed forecasts, while Samsung reported a 250-fold rise in chip

profits only to see its shares slip.

In turn, South Korea's benchmark KOSPI - dominated by

Samsung and SK Hynix - is down over 20% this month, even though

it leapt nearly 18% on Friday. As a reminder, it has still more

than doubled in the past 12 months. That's what I call

volatility.

3. CAPEX QUESTIONS

MIKE DOLAN, ROI Finance & Markets Columnist: As this week's

hyperscaler earnings came under close scrutiny, market anxiety

focused squarely on their cash burn and the debt being raised to

fund the gigantic capex cycle that's ‌building out AI

infrastructure. When does the spend become a problem? AI bulls

reckon not until next year.

Even they have some concerns, though. You should ​watch

hyperscalers' debt levels and credit default swap spreads for

indications of any stress, argues Societe Generale's Manish

Kabra. He reckons that the increase in CDS spreads has depressed

hyperscaler valuations ​to just 18 times forward earnings - the

lowest since ChatGPT was launched in 2022.

4. WINTER IS COMING

RON BOUSSO, ROI Energy Columnist: Europe is heading into winter

with gas inventories at dangerously low levels. LNG imports have

slumped since the start of the Iran war due to disrupted flows

through the Strait of Hormuz, while demand from Asia has ramped

back up, diverting cargoes that might otherwise have headed for

Europe. Even if imports recover during the coming ​months, the

region appears likely to enter winter with inventories well

below its targeted 80% storage level.

This is yet another reminder that Europe's current energy model,

underpinned by imported fossil fuels, is not fit for purpose at

a time when geopolitical risks are rising and energy security is

becoming more important than ever. Europe does have an ambitious

electrification and renewables plan, but the clock is ticking.

5. ALUMINIUM LOOKS ON THE BRIGHT SIDE

ANDY HOME, ROI Metals Columnist: The Iran war is escalating

again, but you wouldn't know it from the aluminium price.

After surging to a four-year high of $3,787.50 per ton in

early June, LME three-month aluminium is now ​trading around

$3,170 per ton, which is exactly where it was before the U.S.

unleashed "Operation Epic Fury" on Iran on February 28.

The ​surprising market calm over the last few days rests on

a growing confidence that the loss of Gulf metal, even if

protracted, can be offset by higher exports from China and

Indonesia.

Opinions expressed are those of the authors. They do not reflect

the views of Reuters News, which, under the Trust Principles, is

committed to integrity, independence, and freedom from bias.