[Update: The SEC rejected the ETF proposal on Friday afternoon, causing the price of bitcoin to slump.]
Bitcoin is at a critical juncture. Any time now, the Securities and Exchange Commission will issue a decision that could throw open the door to a flood of new capital, and change how many investors regard the digital currency.
The SEC’s bitcoin decision, which is over three years in the making, is due by Friday. Here’s a plain English guide to what might happen, including why the decision is so important and how it could affect the price of bitcoin.
What’s the SEC decision?
The agency must decide if the BATS stock exchange can change its rules to offer a bitcoin ETF (exchange traded fund), which would let people buy bitcoin like a common stock. The ETF—called the Winklevoss Bitcoin Trust ETF—is the creation of the Winklevoss brothers, who once fought Mark Zuckerberg for control of Facebook, and now own a large stock of bitcoins.
Why is this ETF such a big deal?
It’s all about liquidity. While there are plenty of places to buy bitcoin, many investment funds can only hold assets that meet certain regulatory standards—such as approval from the SEC. If the agency approves the ETF application, money managers who want to include bitcoin in their portfolio are likely to jump in. Meanwhile, millions of ordinary people will have an easy new way to buy the digital currency. I can’t really phrase it any better than this quote from BitMex, a bitcoin analysis site:
If the SEC approves the Bats rule change, all manner of American muppet retail investors can yolo into Bitcoin via a regulated ETF. The pool of eligible money that can easily obtain exposure to Bitcoin will dramatically rise. There are various predictions about the amount of money that could flow into Bitcoin. In short, it will be Yuge.
Where and when will we see the decision?
The SEC is obliged to make the decision by March 11, which is this Saturday. That means the ruling is almost certain to come out on Thursday or Friday.
According to Blake Estes, an alternative asset expert at the law firm Alston & Bird, the decision will appear on this SEC web page, and everyone will find out at the same time.
Get Data Sheet, Fortune’s technology newsletter.
What are the odds the SEC says yes?
People are calling this a coin toss. Those who think the SEC will approve the ETF point to the skillful work carried out by the Winklevoss lawyers, and to the fact that bitcoin is far more mainstream than it was even two years ago. Today, many more people—including regulators—are familiar with digital currency and how it works. There is also a sense that a bitcoin ETF is sooner or later inevitable.
Pessimists, on the other hand, can point to two sets of concerns that could lead the SEC to give the thumbs down. The first of these relates to how the Winklevoss intend to run the operation. Some people are uneasy that the proposed ETF would use Winklevoss-controlled businesses to source and store the bitcoins that would back the shares. The other set of concerns lie with bitcoin itself. The digital currency has been subject to wild price fluctuations, driven in part by heists and insider antics. According to Estes, the SEC may worry the agency’s approval of an ETF could lead to a bubble inflated by bitcoin novices—a bubble that could then pop.
“Some fear it could be a good opportunity for legacy players to find the next sucker to take it off their hands,” said Estes.
How will this effect the price?
Bitcoin has been on another tear of late, nudging a record of $1,300 per unit—more than an ounce of gold. Some of this likely reflects investor optimism the SEC will approve the ETF, meaning a future price rise is partly baked-in. Nonetheless, there are broad expectations the short term price of bitcoin will go crazy if the SEC says yes.
If the SEC says no, it will have a negative effect, though probably not a very dramatic one. The reason is there are two other ETF application before the agency. One is called the Bitcoin Investment Trust, and was developed by Barry Silbert, a well known figure in the digital currency world. The other, called SolidX, is distinct in that proposes to insure its bitcoin assets.
As noted above, there is a general feeling that approval for a bitcoin ETF of one type or another is inevitable, and so a rebuff by the SEC to the Winkelvoss proposal would only be a temporary setback.
Should I buy bitcoin?
That’s something only you can decide—preferably after a lot of research. Today, many people see bitcoin as another alternative asset class to add to a diversified portfolio. But bitcoin has an extremely volatile history, and has been prone to spectacular crashes, so if you’re averse to risk, it’s probably not for you.
