When Is the Russell Reconstitution in December 2026?

The December 2026 Russell reconstitution takes effect after the U.S. market close on Friday, December 11, 2026, and markets open with the rebuilt Russell US Indexes on Monday, December 14. Membership is based on data as of the close on rank day, Friday, October 30. Preliminary additions and deletions are published after the close on Friday, November 13, followed by a query period from November 16 to 27 and a lockdown starting November 30. FTSE Russell confirmed this schedule on September 1, 2026. It is the first December reconstitution in more than three decades.

When is the December 2026 Russell reconstitution?

The reconstitution is effective after the close on Friday, December 11, 2026. For a U.S. stock trader, that means the regular 4:00 p.m. ET close on December 11 is the last print under the old index lineup, and the 9:30 a.m. ET open on Monday, December 14 is the first session under the new one. December 11 is a normal full trading day, not an early close.

The full sequence, as published in FTSE Russell's December 2026 reconstitution schedule, runs over six weeks:

1. October 30: rank day, with eligibility and ranking data taken as of the market close.
2. November 13: preliminary additions and deletions published after the U.S. close.
3. November 16 to 27: query period for index users to challenge the published data.
4. November 30: lockdown begins and the lists are treated as final.
5. December 11: changes take effect after the close, with the new indexes live from the December 14 open.

The dates follow fixed rules rather than a one-off choice. Under the current methodology, the December rank day is the last business day of October and implementation is the second Friday of December. FTSE Russell originally planned the second Friday of November, then moved the event to December in a November 2025 schedule notice, citing the need to keep the October cut-off and the depth of market liquidity in the first three weeks of December. The same notice keeps FTSE's global equity index review a week later, after the close on the third Friday of December, so the two December events do not coincide.

What happens on rank day, October 30?

On rank day, FTSE Russell takes a snapshot of every eligible U.S. company and ranks it by total market capitalization at the close. Nothing trades differently that day and nothing is announced. The snapshot is what later decides which company lands in the Russell 1000, the Russell 2000, or the Russell Microcap.

The basic entry tests are spelled out in LSEG's guide to the 2026 reconstitution. A company needs a total market capitalization of at least $30 million on rank day, a closing price of at least $1.00 on its primary exchange, and a free float of at least 5%. These are eligibility floors, not the cut-off for a specific index. The largest 4,000 eligible companies form the Russell 3000E; within that ranking, the Russell 1000 covers companies 1 to 1,000 and the Russell 2000 covers companies 1,001 to 3,000. The dollar size at which rank 1,000 or rank 3,000 falls changes every cycle and is known only when the lists come out.

Because the ranking uses closing data from October 30, a stock's move in November does not change its assignment. The exception is corporate activity: under the Russell US Indexes methodology, mergers and spin-offs completed between rank day and lockdown can lead FTSE Russell to recalculate the affected market capitalizations. Existing members near a boundary also get some protection from banding, a cumulative band of plus or minus 2.5% around the Russell 1000 breakpoint and 0.5% around rank 2,000, so a company does not flip indexes on a small change in size.

When are the preliminary lists published?

The preliminary lists come out after the U.S. close on Friday, November 13, 2026, four weeks before implementation. FTSE Russell posts the proposed additions and deletions on its website, and its index clients also receive indicative shares outstanding and free float data. This is the first date on which the market sees actual names, and it is the earliest point at which any statement about a specific stock joining or leaving a Russell index has a documentary basis.

"Preliminary" matters. During the query period from November 16 to 27, index users can question the data, and FTSE Russell can correct it. Once lockdown begins on November 30, the reconstitution is considered final and further changes are made only in exceptional circumstances under FTSE Russell's recalculation policy. A trader who reads the November 13 list should treat it as a strong draft and the post-lockdown list as the version that will actually be implemented.

The timing also shapes the news flow. Because the lists land on a Friday evening, the first full session in which the market can react to them is Monday, November 16. Thanksgiving week falls inside the query period, and the Friday after Thanksgiving, November 27, is a scheduled early close at 1:00 p.m. ET on NYSE and Nasdaq.

What changes in December compared with June?

December is a full rebuild of the index membership by size, but a lighter review of everything else. Both cycles rank all eligible companies by total market capitalization, so a company can enter, exit, or move between the Russell 1000, Russell 2000, and Microcap in either one. The differences sit in the calendar and in how much of the other data is refreshed.

The calendar is compressed. Under Appendix F of the methodology, June's preliminary information arrives five weeks before implementation and lockdown begins three weeks after the query period ends. In December, the lists arrive four weeks ahead and lockdown starts two weeks after the query period. The June event is implemented on the fourth Friday of June; the December one on the second Friday of December.

The data refresh is narrower. In June, free float is fully reviewed and every member gets new style probabilities, which determine the growth and value split. In December, new style probabilities apply only to new additions, including IPOs, and to companies migrating between capitalization indexes; everyone else keeps the June 2026 values. Free float is updated in December only for material changes, with a 3% buffer, and voting-rights research is not repeated for existing members. For a trader, this means the December list should be dominated by size-driven moves rather than by broad reweighting of growth and value indexes.

What does reconstitution day mean for the closing auction?

The practical center of the event is the close on December 11. Because the changes take effect after that close, portfolios that track Russell indexes and want to match the new weights at the moment of the switch have a reason to trade at the official closing price. That is why reconstitution days are associated with heavy on-close interest in the stocks being added, deleted, or moved between indexes. The source documents do not publish a volume estimate for the December event, and the first December cycle has no history to compare against.

What a trader sees in the last ten minutes follows the usual exchange mechanics, only with larger size. NYSE and Nasdaq start publishing closing imbalance data around 3:50 p.m. ET, cut off or restrict new on-close orders on their own timetables, and execute the auction at 4:00 p.m. hi2morrow's guide to why stock volume spikes at 3:50 p.m. ET explains those cutoffs and why a published imbalance is not a forecast of the closing price. The same caution applies with more force on December 11, when imbalances in affected names may be unusually large and can change quickly as offsetting orders arrive.

Order type is the other practical point. A market order sent at 3:55 p.m. executes in the continuous market, not in the auction. Market-on-close and limit-on-close orders are what actually join the closing auction, and many brokers set earlier cutoffs for them than the exchanges do or do not offer them at all.

How are IPOs added between reconstitutions?

Companies that go public between reconstitutions are added in quarterly IPO reviews in March, June, September, and December. The March and September additions take effect after the close on the third Friday of those months. The June and December additions are folded into the reconstitution itself, so IPOs selected for December 2026 enter on December 11 along with every other change.

For the December cycle, the IPO review window runs from August 3 to October 30, 2026, and the IPO market cap cut-off is October 30. An IPO still has to meet the regular eligibility rules. Variable-price, best-efforts, and direct-listing IPOs face an extra condition in the methodology: they must publicly disclose their post-IPO shareholder structure by the December IPO cut-off, or they wait for a later review. Very large IPOs can use a separate fast-entry route and be added after the close of their fifth trading day. How a new listing actually opens on its first day is covered in hi2morrow's guide to why a U.S. IPO doesn't start trading at 9:30 a.m.

A worked example with ABC

Suppose ABC is a U.S.-listed company that is not a member of any Russell index. At the close on October 30, 2026, it trades at $12.00 with 75 million shares outstanding, a total market capitalization of $900 million. It passes the $30 million, $1.00, and 5% free float floors, and its rank places it inside the top 3,000 but below rank 1,000.

On November 13, after the close, ABC appears on the preliminary list of additions to the Russell 2000. Over the next two weeks its price falls to $9.50, cutting its market value to about $712 million. That decline does not remove it from the list, because the ranking was fixed on October 30. ABC remains on the list through lockdown on November 30, joins the index after the 4:00 p.m. ET close on December 11, and is a Russell 2000 member when trading opens on December 14. As a new addition, it also receives style probabilities in this December cycle rather than waiting until June.

The example says nothing about how ABC's price will behave around those dates. Inclusion is a mechanical outcome of ranking rules, not a view on the company, and the flows around it can be offset by other participants well before December 11.

Alexander Styopin's professional view: the most useful thing a trader can do with this calendar is separate the information dates from the execution date. October 30 fixes the data, November 13 reveals the names, November 30 makes them final, and December 11 is when the size actually changes hands. Treating the preliminary list as a trading signal ignores how many participants read the same list the same evening. The more durable edge is operational: knowing your broker's on-close cutoffs, avoiding market orders in thin names on December 11, and remembering that this is the first December cycle, so June's patterns are a weak guide to how liquidity will behave.

Educational material only. Not investment advice. Index schedules and methodology can change, and order types and on-close cutoffs vary by broker and exchange.

Author: Alexander Styopin, hi2morrow analyst and economist with 25 years of experience in the US stock market