Measures of volatility suggest investors remain complacent about risks, but a wedge of swans looming on the horizon could disrupt the markets' calm over the summer months, Societe Generale said.
Markets definitely appear unworried. The , or VIX, spiked last week on news of Israel's incursion into Gaza and that a surface-to-air missile was responsible for the crash of Malaysia Airlines flight MH17. But it remains around pre-financial crisis lows.
Societe Generale is relatively sanguine that the remaining summer months through September will remain swan-free, but it sees several risk factors that could spur a migration.
The biggest near-term risk is a sharp re-pricing of U.S. monetary policy, Michala Marcussen, global head of economics at SocGen, said in a note dated Sunday.
For now, SocGen expects higher wage and inflation data to lead markets to re-price Federal Reserve action, pushing the U.S. 10-year Treasury yield up to 3.25 percent by year-end, from around 2.48 percent now.
"The question is whether the summer data could trigger an earlier and sharper re-pricing of Fed policy tightening than we expect," Marcussen said, noting the bank expects another strong jobs report ahead, while earnings appear to be picking up.
Among other economic risks, China remains at the top of SocGen's "black swan chart."
"Weak property price data released Friday showing property prices falling in 55 out of 70 cities in May was a reminder of the Achilles' heel of the Chinese economy," she said. "A hard landing could come about from a dry-up in property investment, which accounts for close to 15 percent of gross domestic product (GDP)."
The bank assigns a 30 percent probability to a hard-landing scenario, but that's not likely to come soon enough to ruin any summer vacations, she noted.
The second-place economic black swan is the risk of "lowflation" in Europe, but that also isn't likely to wing in near-term, SocGen said.
While the bank's base-case scenario is for Europe to exit lowflation in 2014's second half, "the combination of recent weak data and too little structural reform too late have pushed us to increase the risk of a prolonged lowflation scenario" to a 25 percent probability, just below the likelihood of a China hard-landing, she noted.
Another key risk is widespread expectations that global central banks will rush to the rescue if markets wobble, she said.
"In the case of the U.S. and the U.K., it would take a very significant disappointment on the real economy to trigger further policy stimulus," she said. "A correction in risk premia is unlikely to be seen as a sufficient condition for further policy easing."
Assets underpinned by liquidity rather than strong fundamentals could be in danger of a sharp correction, she said.
But what about the cause of last week's blip higher in volatility, the Ukraine situation?
SocGen doesn't think this particular swan is likely to arrive, with the most likely outcome that on-going sanctions will have short-term manageable economic costs to Russia's economy.
Others also aren't expecting Ukraine tensions to fully erupt.
"It's a little like North Korea risks; it's always there and episodically it spikes," Tim Condon, head of research for Asia at ING, told CNBC, noting the Ukraine tensions are now several months old.
"Leadership in Europe is reluctant to take it to the next step of really difficult sanctions against Russia. I think people are inferring from this that it's not going to get to catastrophic levels," Condon said.
To be sure, SocGen isn't expecting its swans will come home to roost over the next couple months.
"Our baseline scenario for this summer is that economic developments will give little cause for significant market movement," Marcussen said.
Condon also expects volatility will remain low near term.
"Monetary conditions in the G-3 [U.S., Europe and Japan] have crushed volatility," he said. "Investors, I think, are right to think that as long as these policies persist, volatility is going to remain low. And it's going to take something really serious to shock it out of that."
—By CNBC.Com's Leslie Shaffer; Follow her on Twitter @LeslieShaffer1