The Junior Mining Index (JMI): What It Measures and How to Use It

What a level means

An index level is a ratio, not a price. On March 2, 2026 the JMI was set to 1,000. If the level reads 800 today, the members' share prices, weighted the way the rules describe below, are worth 20% less than that day; at 1,200 they are worth 20% more. The number on its own says nothing about any one company. It says what the group has done.

The four sub-indexes were set to 1,000 on the same day, so they are directly comparable: if JMI Gold reads 740 and JMI Copper 860, copper juniors have held up better than gold juniors since March, whatever either metal's price has done. The index charts overlay the metal price so you can see when the shares and the commodity part company.

Three windows are reported on every index: the day, the month and since the base. A week's change appears in the weekly report with the best and worst member of the week named, which is usually the fastest way to learn what moved the number.

Who is in, and who is not

The universe is every public, active company in the company database with a listing on the TSX, the TSX Venture Exchange or the Canadian Securities Exchange and a ticker on record. Private companies, companies listed only abroad and companies that have been deactivated are out.

To enter at a review a company must pass four tests on the reference date:

• Size. A market capitalisation (last close times shares outstanding) between C$5 million and C$500 million. The floor keeps out shells whose price is noise; the ceiling keeps out the names that have stopped being juniors.
• Price. A close of at least five cents. Below that a one-tick move is a 20% move, and a cap-weighted index of such names measures spreads, not value.
• History. Sixty daily closes on record, so a new listing has a quarter of trading behind it before it can move the number.
• Trading. A close on twenty of the last thirty trading days. A name that does not trade cannot be priced.

A member is held to looser bands to stay in: C$3 million to C$625 million, three cents, and ten of the last thirty days. The gap between the entry and the exit rules is deliberate. A company sitting on the C$500 million line would otherwise leave and re-enter every quarter, and each change costs the index a membership event.

A liquidity test (a median of at least C$10,000 traded a day over three months) is written into the rules and switches on for reviews from January 2027, when the site will hold enough volume history to apply it fairly.

Weighting, caps and the divisor

Each member's weight is its market capitalisation as a share of the total, measured at the review. A C$300 million developer therefore counts thirty times a C$10 million explorer, which is how the market itself weighs them.

Uncapped, a handful of the largest names would be the whole index, so no company can exceed 10% of the master or 15% of a sub-index at a review. The weight above the cap is spread across the other members in proportion to their own capitalisations. Between reviews the weights drift with prices, as they do in every cap-weighted index, and are reset at the next review.

The level is the capped market value of the members divided by a number called the divisor. The divisor is the index's memory. Every time the membership changes, a share count is updated, a price is corrected or a stock is consolidated, the divisor is adjusted so that the level is the same the moment before and after the change. Only price moves change the level. Every divisor change is published as an event on the index's page.

Share counts come from the exchange's own figures, refreshed weekly, and a count that doubles or halves between refreshes is held for review rather than applied blindly. A price that jumps fivefold in a day is frozen at its last accepted value until it is explained, because in this sector such a print is more often a consolidation than a discovery.

The four commodity sub-indexes

Every member is assigned one commodity: the metal of its flagship project, or, with no flagship, the metal most of its projects target. Gold, silver, copper and lithium juniors form the four sub-indexes. Companies exploring for uranium, nickel, rare earths and the rest sit in the master index only, until one of those groups has enough eligible members to stand on its own.

A sub-index needs five members to be calculated and fifteen to be cap-weighted. Between five and fourteen it is equal-weighted, and the page says so, because with that few names one large company would otherwise be most of the number. JMI Lithium has been equal-weighted since launch for this reason.

The sub-indexes are the most useful part of the family when you are deciding where to look. If gold juniors have fallen 10% in a month while the gold price is flat, the market is selling the group, not the metal, and a gold junior's own decline over that month is mostly not about the company. If copper juniors are rising while the rest are not, that is the commodity the market is paying for.

Quarterly reviews and what changes between them

The membership is reviewed four times a year. On the second Friday of March, June, September and December the rules are run on that day's data and a proposal is stored: who enters, who leaves, and whose commodity has changed. The proposal is applied after the close on the third Friday, and the new membership counts from the following Monday. The week between is the notice period.

Nothing is added between reviews. A company that lists in April waits for the June review, and then for the sixty-close rule. Members do leave between reviews when the reason is an event rather than a number: a delisting, a takeover that closes, a company that goes private or stops trading.

The next review dates and the stored proposal, once it exists, are on the indexes page. Every past change is listed under each index with its date and reason.

How to use it when you are looking at one stock

The index earns its keep on a company page. Every member's profile carries an Against its index table: the company's price return beside its own sub-index over one, three and six months and since the base date, with the difference. Read it before you read the news.

• Stock down, index down the same: the sector is being sold. The company's story has not changed; the price of exposure to it has. This is when the checklist in how to evaluate a junior mining stock matters most, because the names that survive a sector drawdown are the ones with cash.
• Stock down, index flat or up: the move is the company's own. Look for the cause: a financing at a discount, a drill result that disappointed, insiders selling. The insider activity board and the company's news archive usually hold it.
• Stock up, index down: the rarest and most interesting case. Either the market has found something in the company or someone is promoting it. Volume, who is buying and whether a release explains it tell the two apart.

The weekly report names the best and worst member of each index for the week. A name on that list that you were not watching is worth ten minutes.

What it is not

• Not investable. There is no fund or product on it. It is a measuring stick.
• Not advice. A level, a change or a membership says nothing about whether any company is worth buying.
• Not a total-return index. It tracks prices only. Juniors rarely pay dividends, so the difference is small, but it exists.
• Not currency-adjusted. Everything is in Canadian dollars. A US investor's return differs by the exchange rate.
• Not the whole sector. It covers the companies in this database, not every listing on the three exchanges. Coverage grows as companies are added, and additions wait for the next review.
• Not restated. From the go-live date of October 13, 2026 every published value stands. Corrections are absorbed by the divisor from the day they are made, not written back into history. The values before that date were reconstructed and are marked as such on the charts.

The full rule set, with every threshold, is on the methodology page.

Frequently asked questions

Related

• The JMI indexes: charts, members and changes →
• Index methodology: every rule and threshold →
• How to Evaluate a Junior Mining Stock →
• TSXV Mining Stocks: How the Venture Exchange Works →
• Metal prices →