For the first time, foreigners can now buy and sell shares in listed companies on the Saudi Arabian stock exchange.
It's the last of the grouping of the world's largest economies, the G20, to open up its market to foreigners. Until now, they were only able to indirectly buy shares and would only get the economic benefits.
Industry experts say Monday's move, that allows foreigners voting rights, could be transformative for the region as Saudi companies will be able to profit from the scrutiny and strategy of sophisticated international partners and overseas investment will help push forward the country's economic reforms.
But don't hold your breath. Major emerging market players are not quite queuing around the bourse yet.
That's because there are a multitude of rules to determine who can invest in the gradual opening-up of the Middle East's biggest stock market.
They appear to be quite restrictive. Only institutions that manage $5bn (£3.2bn) of assets (or $3bn if the regulator makes an exception) with a five-year investment record will be given the green light for now.
No single investor can own more than 5% of a company and overall foreign ownership of that company cannot top 49%. Overall, only 10% of equity in the stock exchange, called the Tadawul, can be foreign-owned.
Despite that, buying into the stock market - which is up 15% already this year - is a mouth-watering prospect for qualifying investors.
The market's value of over $560bn and daily trading volumes of about $2.4bn outstrips bourses in South Africa, Russia, Turkey and Mexico.
One key sector, retail, is booming due to high consumer spending.
Subsidised gas has created an extremely competitive petrochemicals sector and the banking sector also looks highly profitable with many bank customers choosing Sharia-compliant, interest-free deposits, which is a bonus for investors.
Investors will also appreciate Saudi Arabia's strong economy. Over the past few years, high oil profits have been used to wipe out the country's debt and build its foreign reserves to 100% of GDP.
There's a growing middle class, salaries keep rising and spending on healthcare and education remains a priority for King Salman. Economists predict the non-oil sector will continue its impressive growth rate, at around 5% this year.
Saudi stock exchange
- Called the Tadawul
- Trading hours are 11:00 to 15:30, Sunday to Thursday
- Lists 165 publicly traded companies
- Real estate is the biggest sector on the index, making up 16%, followed by petrochemicals (15.4%) and banks and financial services (14%)
So why then, are some experts sceptical about what the level of take-up will actually be?
One Middle East-based equities and portfolio manager told me he thought there would be fewer than a dozen institutions certified to invest to begin with, while another boss of a Saudi-based asset management company thinks only half the $50bn of investments on offer to foreigners will be taken up over the next two years.
One reason could be that, as a consequence of high earnings, company valuations are on the high side for investors although they could be justified by potentially offering higher growth rates.
Another possible deterrent is the mandatory requirement that money must be settled up front rather than within two days of the investment, as is the case in other stock markets.
The stock market can also fall sharply as a result of the volatile price of oil in the very short term, though it tends to recover quickly too. Over the last 12 months, oil prices have dropped around 40% and the stock market is down only 2%.
One very experienced international asset manager believes that big pension funds and insurance companies are likely to wait and see how the reforms bed in first.
To be clear, very few doubt this opening is a good move, just that it will take time.
Looking ahead, interest may shoot up in a few years if Saudi moves on from its frontier market status to join the most widely followed emerging markets index, the MSCI.
Mohieddine Kronfol, a founding partner of Franklin Templeton Investments ME, believes a great journey has begun.
He says it could eventually lead to an energised debt market and also predicts that pressure will increase for domestic political and social reforms from ethical investors of the future.