What is mds_stores on Mac?

mds_stores is Spotlight's indexer: it keeps the index of your files that makes Spotlight searches instant. It's part of macOS and safe. You'll often see it with mds, its manager.

Key points

• mds_stores writes and stores Spotlight's index.
• It's busiest after a macOS update, after adding many files, or when you connect a new disk.
• Leave it running: it finishes on its own. You can keep folders out of the index.

What mds_stores does

When files change, Spotlight's helpers, mdworker, read them, and mds_stores adds what they found to the index. It learns which files changed from fseventsd.

Why is mds_stores using so much CPU, memory or disk?

After a macOS update, when you add many files, or when a new disk is connected, it re-indexes. That can take hours, then it settles. While it works, high disk activity is normal: it's reading files and writing the index.

In one reading of a MacBook Pro (M1 Max, 64 GB) on October 10, 2026, mds_stores was running (2 copies), but as a system process it can be measured only with administrator permission, which that reading didn't have.

If it never settles, something keeps feeding it new files: a folder that changes constantly, such as logs, build output or a sync folder mid-sync. More in Is Spotlight indexing slowing down your Mac?

Can I quit mds_stores?

Leave it running: it finishes on its own. To keep folders out of the index, add them to Spotlight's privacy list in System Settings → Spotlight.

How to check it

1. Open Activity Monitor: press Command-Space, type "Activity Monitor" and press Return.
2. Type mds_stores in the search field at the top right.
3. Look at % CPU and Memory. Two copies can be normal.

Questions

Is mds_stores a virus?

No. mds_stores is part of macOS: it's Spotlight's indexer.

Why is mds_stores using so much CPU on my Mac?

Spotlight is rebuilding its index: after an update, many new files or a new disk. It settles on its own, usually within hours.

How do I stop mds_stores from using so much CPU?

Let it finish. If a folder that changes constantly keeps it busy, add that folder to Spotlight's privacy list in System Settings → Spotlight.