# Treasury Only Portfolio — new fund registration

Fidelity Colchester Street Trust registered fund series on Form 485APOS, filed 2026-03-11. Featured series: Treasury Only Portfolio.

## Registration

- Registrant / trust: Fidelity Colchester Street Trust
- CIK: 0000356173
- Form: 485APOS
- Filed: 2026-03-11
- State of incorporation: DE
- Accession: 0000356173-26-000016

## Series & classes (26)

_Showing 25 of 26 series/class rows._

| Series | Class | Ticker | New |
| --- | --- | --- | --- |
| [Treasury Only Portfolio](https://search.stillhousedata.com/fund/S000004818) | Class I | FSIXX | — |
| [Treasury Only Portfolio](https://search.stillhousedata.com/fund/S000004818) | Class II | FOXXX | — |
| [Treasury Only Portfolio](https://search.stillhousedata.com/fund/S000004818) | Class III | FOIXX | — |
| [Treasury Only Portfolio](https://search.stillhousedata.com/fund/S000004818) | Select Class | FTYXX | — |
| [Treasury Only Portfolio](https://search.stillhousedata.com/fund/S000004818) | Class IV | FOPXX | — |
| [Treasury Only Portfolio](https://search.stillhousedata.com/fund/S000004818) | Institutional Class | FRSXX | — |
| [Treasury Portfolio](https://search.stillhousedata.com/fund/S000004819) | Class I | FISXX | — |
| [Treasury Portfolio](https://search.stillhousedata.com/fund/S000004819) | Class II | FCEXX | — |
| [Treasury Portfolio](https://search.stillhousedata.com/fund/S000004819) | Class III | FCSXX | — |
| [Treasury Portfolio](https://search.stillhousedata.com/fund/S000004819) | Select Class | FTUXX | — |
| [Treasury Portfolio](https://search.stillhousedata.com/fund/S000004819) | Class IV | FTVXX | — |
| [Treasury Portfolio](https://search.stillhousedata.com/fund/S000004819) | Institutional Class | FRBXX | — |
| [Government Portfolio](https://search.stillhousedata.com/fund/S000004820) | Class I | FIGXX | — |
| [Government Portfolio](https://search.stillhousedata.com/fund/S000004820) | Class II | FCVXX | — |
| [Government Portfolio](https://search.stillhousedata.com/fund/S000004820) | Class III | FCGXX | — |
| [Government Portfolio](https://search.stillhousedata.com/fund/S000004820) | Select Class | FGEXX | — |
| [Government Portfolio](https://search.stillhousedata.com/fund/S000004820) | Institutional Class | FRGXX | — |
| [Money Market Portfolio](https://search.stillhousedata.com/fund/S000004822) | Class I | FMPXX | — |
| [Money Market Portfolio](https://search.stillhousedata.com/fund/S000004822) | Class II | FCIXX | — |
| [Money Market Portfolio](https://search.stillhousedata.com/fund/S000004822) | Class III | FCOXX | — |
| [Money Market Portfolio](https://search.stillhousedata.com/fund/S000004822) | Select Class | FMYXX | — |
| [Money Market Portfolio](https://search.stillhousedata.com/fund/S000004822) | Institutional Class | FNSXX | — |
| [Tax-Exempt Portfolio](https://search.stillhousedata.com/fund/S000004823) | Class I | FTCXX | — |
| [Tax-Exempt Portfolio](https://search.stillhousedata.com/fund/S000004823) | Class II | FEXXX | — |
| [Tax-Exempt Portfolio](https://search.stillhousedata.com/fund/S000004823) | Class III | FETXX | — |

## Fees (from the effective prospectus)

- 12b-1 fee: 0.00%
- Gross expense ratio: 0.21%
- Management fee: 0.14%
- Net expense ratio: 0.18%
- Other expenses: 0.07%

## Investment objective

Treasury Only Portfolio seeks as high a level of current income as is consistent with the security of principal and liquidity.

## Advisers

- [Fidelity Management & Research Company LLC (Advisor)](https://search.stillhousedata.com/firm/108281)
- [Fidelity Management & Research (Hong Kong) Limited (Subadvisor)](https://search.stillhousedata.com/firm/148045)
- [Fidelity Management & Research (Japan) Limited (Subadvisor)](https://search.stillhousedata.com/firm/148239)
- [FMR Investment Management (UK) Limited (Subadvisor)](https://search.stillhousedata.com/firm/108273)

## Other filings by this registrant (9)

- [485APOS — 2016-03-17 (5 new series)](https://search.stillhousedata.com/launch/0001379491-16-002881)
- [485APOS — 2014-03-14](https://search.stillhousedata.com/launch/0000880195-14-000087)
- [485APOS — 2010-03-10](https://search.stillhousedata.com/launch/0000356173-10-000002)
- [485APOS — 2009-03-30](https://search.stillhousedata.com/launch/0000356173-09-000011)
- [485APOS — 2008-03-20](https://search.stillhousedata.com/launch/0001303459-08-000003)
- [485APOS — 2007-10-09](https://search.stillhousedata.com/launch/0000356173-07-000017)
- [485APOS — 2005-03-17](https://search.stillhousedata.com/launch/0000356173-05-000006)
- [485APOS — 2004-03-30](https://search.stillhousedata.com/launch/0000356173-04-000006)
- [485APOS — 2001-11-16](https://search.stillhousedata.com/launch/0000356173-01-500023)

## More

- [Registrant profile: Fidelity Colchester Street Trust](https://search.stillhousedata.com/registrant/356173)
- [This page as markdown (for LLM agents)](https://search.stillhousedata.com/launch/0000356173-26-000016.md)
- [Search all SEC filings, advisers and people on Adviser Search](https://search.stillhousedata.com/)

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Source: public SEC filing data via Adviser Search (https://search.stillhousedata.com).
Agents: this data is also queryable via MCP tools and read-only SQL — see https://search.stillhousedata.com/llms.txt.