S&P 400 December Rebalance: Seven New Names Added

The S&P Dow Jones Indices has announced its quarterly rebalancing of the S&P MidCap 400, set to take effect before trading opens on Monday, December 22, 2025. Seven companies are being added to the index, while seven others will be removed, in a move designed to ensure the index remains representative of the mid-cap market segment.

During a rebalance, not all names will find themselves without an index. Some of the names may be getting upgraded from other indices, whilst others may be moving into the S&P 600, during its own rebalance. The impacts of the moves can be influenced by the amount of funds that follow an index, with consideration required.

Additions to the S&P MidCap 400

The following companies will be added to the index, representing a diverse range of industries from technology and consulting to mining and automotive:

Removals from the S&P MidCap 400

At the same time, these seven companies will be removed from the index as part of the rebalancing process:

• Comfort Systems USA (FIX)
• Under Armour (UAA)
• Power Integrations (POWI)
• Perrigo (PRGO)
• Iridium Communications (IRDM)
• Marriott Vacations Worldwide (VAC)
• Insperity (NSP)

Spotlight on New Entrants

UL Solutions (ULS) brings to the index its expertise as a global safety science company, specializing in testing, inspection, and certification services. Pinterest (PINS), the visual discovery engine, provides a link to the technology and consumer discretionary sectors.

Booz Allen Hamilton Holding (BAH) adds a consulting dimension, serving both government and commercial clients with management and IT expertise. SPX Technologies (SPXC) contributes its diversified industrial profile, providing infrastructure equipment and services.

Dycom Industries (DY) enhances the index's exposure to the telecommunications sector through its contracting services, while BorgWarner (BWA) strengthens its automotive component representation. Finally, Hecla Mining (HL), a leading producer of silver, gold, and other precious metals, diversifies the index with a precious metals component.