Alliant Insurance Services | 70,951 followers on LinkedIn. Alliant Insurance Services is among the top 5 largest and fastest-growing insurance brokerage and consulting firms in the United States. Fueled by entrepreneurialism and driven by results, Alliant operates on the belief that more is possible and expectations are meant to be exceeded. Our clients and partners have profound confidence in us to deliver in all market climates through the design and delivery of innovative solutions and services across a broad range of industry verticals.