The week's latest tech wobble calmed on Wednesday as service sector surveys impressed, although valuation concerns smoldered. Chip designer Qualcomm's stock fell back 4% overnight despite headline earnings beats as it warned on loss of business from client Samsung.

But a rare trickle of macro data during what's now a record long government shutdown was the focus on Wednesday. Private sector jobs rose above forecast last month, service firms reported rising activity and prices and quarterly Fed lending data showed relatively stable household credit conditions.

With futures showing little more than a 60% chance of another Fed cut next month, Treasuries balked and the long-dated yields hit their highest in almost a month. A string of the Fed's heavy hitters are speaking again later on Thursday.

However, doves will point to rising layoffs as a reason to keep cutting rates and a report on Thursday from Challenger, Gray & Christmas said U.S.-based employers cut more than 150,000 jobs in October, marking the biggest reduction for the month in more than 20 years.

The overall picture left Wall Street stock index futures flat ahead of today's bell despite Wednesday's modest bounce. The dollar fell back across the major currency pairs, while gold nudged higher and Bitcoin retreated again.

Britain's pound perked up after a rough week ahead of a likely knife-edge policy decision from the Bank of England later. Markets see 40% chance of a UK rate cut as soon as Thursday as this month's critical government budget plan is expected to tighten fiscal policy.

Elsewhere, Asia stocks firmed and China's markets outperformed again. European stocks slipped.

Wednesday's Supreme Court hearings raised doubts over the legality of President Donald Trump's sweeping tariffs, with betting markets seeing just a one-on-four chance that they will give the use of emergency powers clearance. That potentially creates a hiatus in the plan as Trump would then need to seek other routes to impose the tariffs.

While the Supreme Court typically takes months to issue rulings after hearing arguments, the administration asked it to act swiftly. The timing of a decision remains unclear.

Pressure to end the record 36-day government shutdown was building meantime, with Transportation Secretary Sean Duffy saying he would order a 10% cut in flights at 40 major U.S. airports, citing air traffic control safety concerns.

Bubble or bonanza? AI could be both. 

Artificial intelligence may well be the future of business and the wider economy, yet the sky-high stock prices it's generating may still represent an unsustainable bubble.

Today's constant fretting about whether frothy tech stocks are in a bubble is rooted in fears that AI may not live up to the hype and that business returns will therefore never justify the blistering investment we're seeing on advanced chips as well as the infrastructure and energy needed to support AI's vast processing needs.

Acres of columns will be written on the "AI hype" question in the coming months, with most likely concluding that "it's too early to tell". 

Some early studies say companies are not yet reaping significant returns from AI, even as an estimated $3 trillion of investment is expected to be ploughed into the technology over the next three years. But generating returns was always going to take time.

As to the consensus view? Maybe that's best left to AI itself.

In response to the question "Is AI a bubble?", Google's "AI Mode" concluded: "While the core AI technology is considered a genuine and potentially revolutionary development, there is significant debate about whether the current market valuations are sustainable or if the sector is experiencing a bubble-like period of over-exuberance and speculation."

Productivity gains and revenue growth over the coming years will ultimately determine AI's value, it adds, clearly reluctant to talk itself out of a job just yet.

Perhaps it's more useful to look at the lessons of past bubbles. History suggests that revolutionary technologies typically attract a flood of capital, not all of it "smart money". 

So even if the technology endures and ultimately transforms the world, some of the priciest stocks from the bubble years can still be left high and dry. The companies may not go bankrupt, but over-eager valuations can mean their share prices take years to recover - if they ever do.

That certainly seems to be the conclusion of short-seller Michael Burry - of "The Big Short" fame - on today's AI darlings Nvidia and Palantir. He doesn't think they're bad companies. He simply thinks their stock is overpriced.

It's impossible not to compare today's valuation frenzy to the 1990s dotcom bubble in tech, media and telecom stocks that burst spectacularly in early 2000.