Asian stocks were mixed on Wednesday ahead of a policy decision by the U.S. Federal Reserve.
The widely anticipated trading debut of SoftBank Corp, the mobile unit of Japanese conglomerate SoftBank Group, ended in disappointment. The company's shares closed 14.5 percent lower than its initial public offering price of 1,500 yen ($13.36). It was the most heavily-traded stock on the Tokyo Stock Exchange.
SoftBank Corp's 2.65 trillion yen ($23.6 billion) IPO is the largest ever in Japan and the second-largest in the world behind Alibaba's $25 billion IPO in 2014.
"I'm not 100 percent surprised that it's down this much. If they'd been able to hold above that 1,500-level (IPO price), it could have been a different story," said Andrew Jackson, head of Japanese equities at SooChow CSSD Capital Markets Asia.
"Once it dipped below it, a lot of these retail investors, first-time investors who don't really know much about the markets, are probably in a big hurry to get out," Jackson told CNBC's "Street Sign," noting that around 90 percent of those that subscribed to SoftBank Corp's IPO were retail investors.
In the broader Japanese market, the Nikkei 225 finished the day 0.6 percent to 20,987.92 and the Topix closed 0.41 percent down to 1,556.15.
Greater China markets were mixed. The Shanghai composite ended the day 1.05 percent lower at 2,549.5634 and the Shenzhen composite fell by 1.376 percent at the close to 1,294.4853. Meanwhile, Hong Kong's Hang Seng Index was 0.12 percent higher in late Asian trading hours.
Shares of top Chinese oil firms fall following the plunge in oil prices overnight. Petrochina shares fell 3.28 percent in Hong Kong and 2.1 percent in Shanghai. Shares of China Petroleum and Chemical Corp slipped 4.85 percent in Hong Kong and 2.75 percent Shanghai.
Energy stocks in Australia were also mostly lower. Origin Energy tumbled by 5.69 percent at the close, while Woodside Petroleum fell by 1.82 percent. The slipped by 0.16 percent to 5,580.6 at the end of Wednesday's trading session.
South Korean stocks, meanwhile, ended the session higher with the Kospi index rising 0.81 percent to 2,078.84.
Fed decision coming
It was another volatile trading day in the U.S., which saw the three major indexes ending the day broadly flat. The closed 0.01 percent at 2,546.16, the Dow Jones Industrial Average added 0.35 percent to 23,675.64 and the Nasdaq composite inched up 0.45 percent to 6,783.911 points.
One widely watched event coming on Wednesday in the U.S. is the monetary policy decision by the Federal Reserve. The central bank is expected to hike its benchmark overnight lending rate for a fourth and final time in 2018, and its outlook for 2019 will also be scrutinized by investors.
"The key for me is not whether they hike or don't hike, I'd be very surprised if they pause ... the question is what do they convey about the path moving forward. Do they lower the dot projection from three to two or is it even more dovish than that? So the story really isn't about the December hike, it's what 2019 and critically what 2020 looks like," Frances Donald, head of macroeconomic strategy at Manulife Asset Management, told CNBC's "Squawk Box."
China's opening up
China is reportedly starting its Central Economic Working Conference this week after Chinese President Xi Jinping's Tuesday speech to mark the 40th anniversary of the country's market opening and reform.
David de Garis, director of economics and markets at National Australia Bank, said he expects China to "reset growth and reform objectives" this week. That could provide further hints into the status of China's ongoing tariff fight with the U.S., which is now on hold until March.
Among the details that could come out from China include the growth target for 2019, growth-supportive policies and reform measures essential for a deal with the U.S., de Garis wrote in a morning note.
Currencies
Ahead of the Fed decision, the U.S. dollar index — which measures the greenback a basket of major currencies — slipped to 96.871 from the precious close at 97.104.
The was stronger versus the U.S. dollar at 112.37 compared to 112.51 previously, while the inched up to 0.7191 from 0.7180.