The inclusion will mean that A-shares make up just 40 basis points of the MSCI Emerging Market Index - not a huge amount. But, while on paper the weighting might seem low, the ramifications for China's markets and foreign investors could be huge in the longer term. One of the big questions is what sort of time frame are foreign investors looking at.

CGTN's Joel Flynn has more. June 2015 - Chinese stocks are about to plunge 30 percent in the country's worst market turmoil in years. Trillions of dollars were wiped off the value of mainland shares - and talk was of the next financial crisis. The plunge was driven by issues of currency and interest rates - but it was also being fuelled by investors' borrowing to buy stocks. This is part of the cautionary tale that's now at the forefront of minds in Beijing and abroad, as Chinese A-shares begin to be included in MSCI's Emerging Market Index. 

RAKESH PATEL, GLOBAL HEAD, EQUITY ADVISORY, HSBC "I think there's a general theme there about China wanting to open up capital markets. That's the general theme, and they do that one, to try and change behavior onshore, in terms of investing from a risk perspective, and two to go and encourage foreign inflows into China."

While investors might have reason to be jittery though, for most this is a move defined by opportunity. Analysts estimate about $20 billion will initially flow into Chinese stocks through this initial weighting. That could rise to $300 billion if there is full inclusion, which most people expect.

One company has already been trying to leverage interest. Four years ago KraneShares and Bosera launched an ETF that tracks the progressive partial inclusion of A-shares into the MSCI Emerging Markets Index.

The importance of the inclusion, it says, lies in the growth of passive investment.

BRENDAN AHERN, CIO, KRANESHARES "Those investors need to mechanically adhere to the index methodologies and I think that's demonstrated by MSCI's up to $14 trillion benchmarked to their indices. That's a big, big number. 17 percent of MSCI Emerging Markets? Potentially very very strong inflows from passive, as well as active investors."

JOEL FLYNN, HONG KONG "Foreign investors already have access to Chinese shares through Hong Kong's landmark Stock Connect programmes with Shanghai and Shenzhen. Ahead of the MSCI inclusion, these have been quadrupled in size to provide both liquidity for passive investing, and because active investment is expected to grow as well."

RAKESH PATEL, GLOBAL HEAD, EQUITY ADVISORY, HSBC "In general we're still underweight. The risk is actually if you don't get fully weighted in China versus your trackers, you'll have a tracking risk, so that's one risk if you like. But form an active fund manager perspective, when you're picking stocks in China you obviously have to go and tread a bit carefully. It's a new market for most global investors, so if you're sitting in Boston, or New York or San Francisco, China's a long way."

The timing is far from perfect. Markets are still nervous about ongoing trade frictions between Washington and Beijing, which on Wednesday helped plunge Chinese equities to their worst losses in almost two years. There's also ongoing worries about credit risks in the broader Chinese market. But as far as foreign investors are concerned, the biggest fear of all could be of missing out on this opportunity.