Santa came later this year for the U.S. stock market.

All three major U.S. indexes gained at least four percent on Wednesday, the first time that has happened since 2011. The Dow Jones Industrial Average took its biggest single-day leap in history, zooming up almost 1,100 points. The technology-focused Nasdaq rose by nearly six percent. In addition, more than 500 stocks in the S&P 500 finished positive, with 99.8 percent of stocks advancing.

"Typically, it looks like a bear market rally, you rarely see a huge rally in bear market. Because the market has been falling so much and people said "ok" it has been dropping and even if it rises two percent, it is still a good time to buy in. But the question is that is it a really bear market? It is hard to predict whether the market is going to be a bull market or a bear market," said Chen Jiahe, chief strategist of Cinda Securities.

Some analysts also believe that Christmas holiday sales were the strongest in years, which helped mollify concerns about the health of the economy.

However, it is hard to look at one day to say the bear market is all over. The market gave investors a ride on roller coaster as U.S. stock-index futures fell on Thursday after S&P 500 stages best comeback, indicating that investors are not prepared to build on the biggest rally in American equities. 

Dow Jones Industrial Average and Nasdaq 100 index dropped 0.6 percent and 0.7 percent separately. S&P 500 Index futures fell as much as 0.6 percent today.

2018 has been a volatile year for U.S. stock market. Despite the surge on Wednesday, the S&P 500 index was on pace for its biggest percentage decline in December since the Great Depression. Among the volatile market, FAANGS, the big tech stocks which includes Facebook, Apple, Amazon, Netflix and Google was particularly badly hit in 2018.

"The first reason to rattle the markets was the problems with China, China trade, China tariffs and the incoherent policy we've seen coming out of Washington. Next we've seen the possibility of a global slowdown which is a little bit out of my wheelhouse but is clearly something the market is paying attention to and then I think the most important thing is interest rates," Peter Tuchman from Quattro M. Securities explained. "Historically, interest rate changes have been one of the biggest things to affect the market on a quarterly basis."

The rally also influences Asian trading, according to Chen Jiahe, chief strategist of Cinda Securities.

"The reflection on Asian market shows that the market is not very happy, probably reflects that the traders are not really confident about what has been expressed by this astonishing rally. Only Japan has been rallying a lot, but the whole Asian market has been dropping," he said.

Focusing on Hong Kong market, expert said that companies are trading at extremely low valuation with big state backed companies trading at three to five times PE ratio, 0.4 to 0.5 PB ratio and about six to 10 percent dividend yield, which provides a very solid foundation for future growth.