The Google-based communication app developer is looking to add to its $180m of equity funding with a round that would value it at up to $2.6bn.

US-based office communication app developer Slack Technologies has begun talks with prospective investors over a funding round that would value it at up to $2.6bn, TechCrunch reported yesterday.

The funding would follow a $120m series D round co-led by Google Ventures, the corporate venturing arm of internet company Google, in November at a $1.1bn valuation, and which also included Kleiner Perkins Caufield & Byers, Andreessen Horowitz, Accel Partners and The Social+Capital Partnership.

Investment firms Coatue Management and Horizons Ventures…