The S&P 500 index was on pace for its biggest percentage decline in December since the Great Depression despite Wednesday's surge. But just a few months ago, reports were saying that the American stock market had ushered in the longest bull market ever - more than three thousand days. As CGTN's John Terrett wraps up, 2018 has been a volatile year.

Meet our guide to U.S. stock prices in 2018 - not very talkative I grant you - but packed with information nonetheless - it's one of the digital Big Boards on the trading floor of the New York Stock Exchange.

JOHN TERRETT NEW YORK "Take a look at the Big Board and on the right hand side - in red - you see VIX - that's the Volatility Index or the fear index - and there's been a lot of fear in 2018."

Broker Peter Tuchman - who unlike the Big Board - is VERY talkative - explains why.

PETER TUCHMAN QUATTRO M. SECURITIES "The three most important - and I think the first one to rattle the markets were 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. Historically, interest rate changes have been one of the biggest things to affect the market on a quarterly basis so it's something we have to keep our eye on."

There have been some extraordinary gyrations in U.S. stock values this year. Swings of 500 points or more - from red to green and back again - or the other way round - have been common.

In the closing weeks of 2018, it was said you'd have to go back to 1931 - 87 years - to find a worst December for the S&P 500.

JOHN TERRETT NEW YORK "At some point in the year almost every sector has been beaten up, from the banks to the retailers, to the healthcare, from the transports to the housing, but there is one sector that the Big Board is telling us was particularly badly hit by the volatility of 2018 and that's the FAANG - the big tech stocks that only a year ago were rising so fast."

Santosh Rao monitors FAANG stocks- Facebook, Apple, Amazon, Netflix and Google - for a living - he says they are on track to end the year far lower than they began.

SANTOSH RAO, HEAD OF RESEARCH MANHATTAN VENTURE PARTNERS "FAANG stocks are highly volatile stocks and are reacting to a highly volatile stock market. These stocks ran up a lot so totally logical that investors are taking profits in the face of geopolitical, trade wars and FED crosscurrents. Drilling deeper there are company specific issues as well."

Of course, nothing takes away the fact that three giant U.S. companies briefly hit one trillion dollars in value this year - Apple, Amazon and Microsoft all had market cap valuations bigger than some small countries in 2018.

So what may happen in 2019? Peter Tuchman - who has worked at the New York Stock Exchange for over thirty years says too many unknowns make predictions tough, especially regarding the Trump White House.

PETER TUCHMAN QUATTRO M. SECURITIES "Is this administration done? Are we going to continue the indictments and the attack on what's going on there? How is that going to affect the markets? That's an unknown, that's a wild card. Our economy, is it going to slowdown? I don't kinda get a sense of that. Are they going to pause on the interest rate raises as aggressively as they've been? Probably! What's going to happen with China? I think that'll work itself out as long as we don't keep pressing on the gas and the break at the same time with our policy decisions."

Whatever happens, it'll be reflected by the numbers in green or red high on the wall of the trading floor. John Terrett, CGTN at the NYSE.