Top insurance brokers, No. 5: Alliant Insurance Services Inc.

2024 brokerage revenue: $5B
Percent increase: 29.3% 

Strong growth in its construction and personal lines businesses helped Alliant Insurance Services Inc. add more than $1 billion to its top line in 2024.

The brokerage began in 1925 as a storefront agency in San Diego and is celebrating its 100th anniversary this year.

Alliant first broke into the Business Insurance ranking of the world’s 10 largest brokerages in 2022 and has continued to grow at 20% or more annually since then.

Irvine, California-based Alliant reported $5 billion in brokerage revenue for 2024, a nearly 30% increase over the prior year, climbing to No. 5 in Business Insurance’s ranking of the world’s largest brokers.

Alliant reported 21.9% organic growth in 2024, and its headcount increased 15% to just over 14,000 employees.

“This growth isn’t being fueled by making a bunch of acquisitions. This growth is being fueled by winning new business,” said Alliant CEO Greg Zimmer, calling the organic growth “exceptional.”

Organic growth outpacing headcount is a sign of increasing efficiency, he said: “If our revenue growth is higher than our employee count growth, then that tells me we’re becoming more efficient as a business.”

Commercial retail brokerage revenue increased 23.8% to $2.35 billion in 2024, while wholesale revenue rose 14.1% to $558.6 million. Personal lines increased by over 40% to $822.7 million.

Alliant’s fledgling reinsurance business, launched in 2023, more than tripled in 2024 as reinsurance brokers played a larger role in overall placements, Mr. Zimmer said.

“Every operation within our business grew last year, so we’re getting it from everywhere,” he said.

“The company’s organic growth was supported by double-digit growth across all its business segments, benefiting from strong new business and success with the company’s specialty-oriented strategic focus,” said Julie Herman, New York-based director at S&P Global Ratings, a division of S&P Global Inc.

Mr. Zimmer singled out Alliant’s construction practice.

“We continue to pick up large contractors as new clients and pick up new projects … and continue to add talent to that space. The construction business for us continues to grow dramatically,” he said.

He also noted that Alliant’s consumer businesses — non-standard auto, Medicare and Affordable Care Act health coverage — saw strong growth. “They’re all growing at double-digit clips,” Mr. Zimmer said.

In the marketplace, Mr. Zimmer said, “property rates are moderating, but even that can vary dramatically by region,” and that “in general, the casualty lines are continuing to firm.”

Solid insurance sector performance “has fueled really favorable tailwinds in terms of the growth and also the profitability of brokers from an organic growth perspective,” said Harrison Brooks, a partner at Atlanta-based Reagan Consulting Inc.

Mr. Brooks said property/casualty commercial lines grew at 8.2% in the first quarter alongside 9.2% growth in personal lines, according to Reagan data. “If you’re a large commercial shop, it’s kind of been a paradise for you,” he said.

“They’ve really diversified their book substantially,” Ms. Herman said, highlighting the consumer and auto businesses. “From a product perspective, they’ve added several new segments over the years, and they’re now operating on all cylinders.”

While there is still some concentration in its home state of California, Alliant has diversified geographically and operates in 38 states, Ms. Herman said. She called the broker “a positive outlier from an organic growth perspective.”

The uncertainty gripping the U.S. economy, much of it hinging on a volatile tariff environment, has not blunted growth or hurt the broker, Mr. Zimmer said. As a largely domestic service business, “the tariffs have really not had an impact on our business, and how we organize and what we do day to day,” he said.

On the technology front, Alliant is embracing artificial intelligence, beginning with internal applications, Mr. Zimmer said.

“We have 12 to 15 initiatives in various stages, predominantly internally focused at this time on efficiencies, more so than client-facing initiatives,” he said.

Of AI, Mr. Zimmer said, “We are absolutely focused on it, in a cautious manner, but I think it’s here to stay, and it’s only going to become a bigger and more significant component of people’s business.”