While black swans are inherently unpredictable, Nomura has pointed to 10 potential grey swans to worry about for 2017.
The black swan concept was popularized by finance professor Nassim Nicholas Taleb's book "The Black Swan: The Impact of the Highly Improbable." The book, noting that it was widely assumed all swans were white until the discovery of black swans, highlighted that outlier, or previously unthought-of, scenarios can some to pass with extreme economic impacts.
But Nomura pointed to what it called the black swan's cousin, the grey swan.
"These are the unlikely but impactful events that, in our opinion, lie outside the usual base case and risk scenarios of the analyst community," it said in a note Wednesday, noting it was avoiding the more usual, well-discussed outliers such as a euro-area breakup, a Donald Trump impeachment or a China implosion.
Potential shock 1: U.S. productivity might boom
Nomura noted that global productivity has been anaemic since the 2008 global financial crisis and its base case is for U.S. productivity to remain on the low side for years ahead.
But it noted that in the early 1990s, productivity was expected to remain low, but it quickly doubled during that decade's tech boom.
"We know that low investment has been a key contributor to poor productivity. It certainly has been true that investment in buildings and equipment is at recessionary levels," Nomura said. "But investment in intellectual property and R&D is running at close to post-crisis highs. The fact that this form of investment is less tangible makes it easy to miss. It could also provide the foundation for a surge in productivity."
The market implications would be "far-reaching," with likely stronger stock markets and more aggressive tightening from the U.S. Federal Reserve, Nomura said.
Potential shock 2: China might float its currency
Nomura said the chances of China letting its currency become completely market-determined anytime soon were "very low." But it added, if China were to suddenly remove its 2 percent onshore trading band and stop intervening in the currency market, the yuan would depreciate sharply rapidly.
"The risk is that rapid renminbi (yuan) depreciation would lead to a sell-off in local markets and feed through to greater negative regional and global market contagion," Nomura said.