The party seems only to be roaring ahead — Japan's Nikkei index today closed at its highest level since February, and U.S. and European stock markets finished the week up as well. But stubborn trouble in emerging markets has some economists worrying about an eruption of financial contagion resembling past global crises.

What's going on: Plunging currencies and stock markets in the emerging economies suggest a threat to the nine-and-a-half year stock market bull run, along with the global economy, with Europe especially in the line of fire, economists say.

The backdrop: When economists worry about "financial contagion," they are thinking in part about 1997, when a crisis with the Thai baht set off a regionwide Asian economic crisis that, in 1998, reached Russia and sent its economy into a tailspin. The 2008-'09 financial crash was an extreme example of contagion, spreading and nearly crashing the entire global economy.

The current picture of trouble begins with the end of low, flat interest rates, which have fueled the global economy since the financial crash: the U.S., the EU and Japan have all begun to raise rates, with the Fed expected to increase them another notch later this month.

The other main indicator of a threat is a spike in dollar-denominated debt issued by emerging nations — it has soared to $11 trillion from just $3 trillion in 2009, according to Joe Brusuelas, chief economist at RSM.

As interest rates rise, countries like Turkey, South Africa, Brazil and Argentina will have to make higher payments on their debt, potentially putting them in a serious crunch. Advanced economies have relatively high exposure to the emerging economies: 10.3% of the UK's total bank assets are linked to emerging markets; 6.9% of the EU's; and 5.3% of U.S. debt, Brusuelas said. "That is quite a bit," he said.

• Of particular worry is Turkey, whose debt is 53.4% of GDP, Brusuelas said.
• "If Turkey goes bankrupt — if it defaults — France, Germany and Italy are all on the hook," he said. "Europe will be in a major problem."
• Spain is holding $82.3 billion in Turkish debt, France $38.4 billion, Germany $17.1 billion, Italy $16.9 billion, the UK $19.2 billion, and the U.S. $18 billion.

In an Aug. 31 note to clients, Christian Keller, head of economic research at Barclays, suggested that the U.S.-instigated trade war can exacerbate the emerging market crisis, and help to spread the financial trouble globally.

"Mounting concerns about global trade and financial links in a world of increased protectionism and tightening dollar liquidity have the potential to create wider contagion, threatening the U.S.-driven global expansion."

The bottom line: Historically speaking, financial crises seem to arrive when the consensus mood is at an obliviously partying high. Which doesn't seem very far from the atmosphere now.

For centuries, business titans have risen in acts of ruthlessness, then washed their reputations in displays of charity, endowing monuments like libraries (Carnegie), museums (Getty), universities (Rockefeller) and plain-old philanthropies (Ford).

Not Jeff Bezos. For now, the Amazon kingpin says he plans to donate a tiny part of his $160 billion fortune, and continue to do business with the rest, Axios' Erica Pandey writes.

Between the lines:

• Yesterday, Bezos announced The Day One Fund, committing $2 billion — or 1.25% of his fortune — to family homeless shelters and Montessori-style preschools in underserved communities.
• By comparison, Bill Gates has endowed the foundation he shares with his wife Melinda with $50 billion. Warren Buffett has donated $34 billion since 2006, and plans to give away his whole fortune, and Facebook's Mark Zuckerberg has committed $45 billion.

The big picture: Bezos explains that he is seeking long-term impact through ventures like his space exploration company.

"I'm going to give away a lot of money in a non-profit model, but I'm also going to invest a lot of money in something that most investors might say is a terrible investment — like Blue Origin — but that I think is important."

"For the first time in history, we're big compared to the face of the planet," Bezos said. We have two choices as humans, he said: stop growing now, and keep population and energy consumption constant, or move into the solar system.

• Bezos likes option No. 2. And he dreams of his company being the one to get us there.

Maybe Blue Origin won't be profitable, and he will turn it into a non-profit, Bezos said. But he hopes it will make a killing.

Everything fell between the cracks. Never mind — here is a recap of the top stories at Future this week:

1. Fiddling with your brain: Brain simulations are a step from messing with your very essence

2. A world of tech fiefdoms: The U.S. and China may divvy up the world

3. Back to the jungle: Without a global titan, our natural state is violently tribal

4. The race for quantum dominance: Military superiority and a new industrial revolution

China's worrisome pension shortfall (Gabriel Wildau, Yizhen Jia - FT)

Germany is the latest to Big Surveillance (Janosch Delcker - Politico Europe)

Retailers could lose $700m to Florence (Daphne Howland - Retail Dive)

Behind that insane storm surge animation (Brian Barrett - Wired)

The future of chicken (Deena Shanker - Bloomberg)

As of late, T.G.I. Friday's — that American stalwart of strip malls and airports — has a surprisingly modern engine behind it: artificial intelligence.

Axios' Kaveh Waddell writes: As researchers keep pushing AI forward, increasing types of businesses are experimenting with basic forms of the technology to cut costs, resolve problems efficiently — and achieve a little wow factor.

The big picture: To hear Friday's tell it, few aspects of its global enterprise haven’t been injected with AI.

• Algorithms help managers order ingredients, deal with food waste, schedule staff members, and identify fraud.
• By analyzing staff tips and the average check of the tables they wait, managers get automated recommendations for who gets what shift.

The company is also experimenting with micro-targeting to lure customers more often, Sherif Mityas, chief experience officer at Friday’s, tells Axios.

• An experimental system can identify frequent customers by their phone. Staff can then greet them by name and lead them to a table where their favorite cocktail is already waiting.
• Combining cellphone location information with data on who has connected to restaurant wi-fi can allow Friday's to nudge people within a 5-mile radius to come in for dinner.