# A3 Capital

A3 Capital is a Single Family Office based in Brussels, Belgium.

## Overview

- **Organization type:** Single Family Office
- **Headquarters:** Brussels, Belgium
- **Region:** Europe
- **Address:** Brussels, Belgium
- **Founded:** 2015
- **Assets under management:** Undisclosed
- **Website:** nerias.com.br
- **LinkedIn:** https://www.linkedin.com/company/a3capital

## Regulatory record

- **Reports private funds:** No

## About

A3 Capital was established in 2015 by Marnix Galle. The firm manages private wealth generated from Galle’s real estate activities at Allfin and his leadership role at Immobel. Galle’s father Roger Galle founded the construction company Galle en Zonen, providing the family’s historical base in Belgian property and construction. The office allocates across real estate, private equity, infrastructure and private credit. Investment stages include acquisition, buyout, development, seed and Series A. Confirmed positions and partnerships involve joint ventures such as Immsioen SA with Sioen Industries, projects with BPI Real Estate on the Brouckère development, and work with Besix on the Lebeau project in Brussels. Additional activity spans Fidentia on the Infinity project in Luxembourg and CA Immo on the Eden Tower in Frankfurt. Geographic reach covers Europe, North America, Asia and South America. Deployment size and team headcount remain undisclosed. One additional office operates at Central Point in Warsaw. Marnix Galle holds board roles at Sioen Industries NV and serves on the boards of Guberna, Europalia International and the Association of the Nobility of the Kingdom of Belgium. He is also a Global Governing Trustee of the Urban Land Institute. No operational events from the last 24 months appear in available records. The structure links the Galle real estate lineage directly to the Sioen industrial family through Galle’s marriage to Michèle Sioen, CEO of Sioen Industries. This connection creates a hybrid network spanning listed industrial assets and property development without external fund vehicles or activist mandates.

## Sectors

- Real Estate
- Hospitality
- Infrastructure
- Private Equity

## Offices

- Warsaw, Poland

## People

- Marnix Galle — Principal
- Michèle Sioen — Family Member
- Alfred Galle — Family Member

## Questions

### Who runs investment decisions at A3 Capital?

Marnix Galle directs investment decisions. He maintains oversight through direct involvement in real estate and private equity allocations.

### How does A3 Capital source proprietary deal flow?

Deal flow originates from Marnix Galle’s existing joint-venture relationships with groups such as Besix, BPI Real Estate and Sioen Industries.

### Is A3 Capital structured as a single family office or does it operate more like a venture firm?

A3 Capital operates strictly as a single-family office. It does not raise external capital or function as a venture firm.

### Does A3 Capital participate in fund commitments or only direct deals?

The firm executes direct investments and joint ventures. No external fund commitments are recorded.

### What investment stages does A3 Capital typically target?

Stages include acquisition, buyout, development, seed and Series A.

### Does A3 Capital maintain philanthropic structures, and how are they separated?

Philanthropic vehicles include the Galle Art Foundation, Pelicano Stichting and ToekomstATELIERdelAvenir. These sit alongside the investment office without disclosed overlap in capital deployment.

## Related profiles

- [980 Investments](https://altss.com/profile/980-investments)
- [Aadidev Family Office](https://altss.com/profile/aadidev-family-office)

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Last updated: 2026-07-06T00:30:22.297Z

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