The sale is expected to close in January 2019 and is subject to the satisfaction of customary closing conditions, including applicable regulatory filings.

George Colony (pictured), Forrester’s chairman and chief executive officer, said: “This announcement was driven by our clients. Empowered customers and the disruptive power of technology are forcing business and technology leaders to take decisive action and make deep-rooted changes while delivering quarterly results.

“The combined value of Forrester’s strategic and SiriusDecisions’ operational capabilities will help our clients change and grow in tumultuous times.”

Rich Eldh, SiriusDecisions’ cofounder and co-CEO added: “Allying with Forrester changes the game for our clients and accelerates our growth across industries, regions, and business functions. Beyond the powerful synergies of our two firms what will make this work is our shared passion for our clients’ success.”

While Forrester works with business and technology leaders to build customer-based strategies, SiriusDecisions focuses on optimising marketing, sales, and product operations.

Forrester said the deal opens opportunities for expansion: cross-selling services and broader access to research and advisory content, data, and tools; accelerating international growth plans including distributing SiriusDecisions’ products in EMEA and APAC; expanding SiriusDecisions’ platform, methodologies, data, and best-practices tools to new roles; and expanding SiriusDecisions to new vertical markets.

It will double its potential market and Forrester’s chief financial officer, Michael Doyle, said the acquisition would add about $100m to its revenue in 2019.