Alliant Insurance Services is one of the largest insurance brokers in the United States, not an insurance company that underwrites policies or pays your claims. It arranges coverage and risk-management and employee-benefits services, mostly for businesses and organizations, by placing them with actual insurance carriers. Founded in 1925 and headquartered in Irvine, California, Alliant ranks around the 5th-largest US broker and is the largest privately owned one. It’s a private company owned by its management and producers alongside private-equity investors led by Stone Point Capital, with PSP Investments and KKR also holding stakes. Here’s the full picture.

Alliant Insurance Services: Key Facts at a Glance

Question	Short answer
Broker or carrier?	Broker, it arranges coverage, doesn’t underwrite it
Founded	1925
Headquarters	Irvine, California
Size ranking	Around #5 largest US broker; #1 privately owned
Owned by	Management/producers + Stone Point Capital, PSP, KKR
Public or private?	Private company

You got a policy or a job offer from “Alliant,” and you’re checking them out

Here’s the moment that brings most people to this page. Maybe your employer’s benefits run through Alliant. Maybe a business you own just got a commercial insurance proposal from an Alliant producer. Or maybe you’re weighing a job there and want to know if they’re legit and how big. Either way, you searched the name and hit a wall of finance-directory pages that don’t answer the plain questions. What is Alliant? Who owns it? And are they any good?

Let’s clear it up in plain English. The most useful thing to grasp up front is simple: Alliant is a broker, not a carrier. That one distinction answers half the confusion in the search results. This guide covers what Alliant does, who owns it, how big it really is, and how to judge whether it’s a good fit, without the directory-page jargon.

Is Alliant a carrier or a broker? (The key distinction)

Alliant is a broker (an insurance brokerage), full stop. This matters more than any other fact on this page, so here’s the difference in plain terms.

• An insurance carrier (like State Farm, Chubb, or Travelers) underwrites policies: it takes on the risk, collects premiums, and pays claims. The carrier is who your coverage is actually with.
• An insurance broker (like Alliant) doesn’t take on risk or pay claims. It works on your side. It assesses your risks, shops the market, and places your coverage with the right carrier. Then it helps you manage the policy and claims over time.

So if you have coverage “through Alliant,” your actual insurer, the one who pays a claim, is a carrier Alliant placed you with. Alliant’s value is the expertise and market access it brings. That’s most useful for complex commercial and specialty risks. Think of a broker as your professional buyer’s agent for insurance, not the insurance company itself.

What does Alliant Insurance Services do?

Alliant operates as an insurance brokerage and consulting firm. In practice, it does a few connected things for its clients (who are mostly businesses, organizations, and public entities rather than individuals):

• Places property & casualty insurance, arranging commercial coverage like general liability, property, workers’ compensation, and specialty lines.
• Manages employee benefits, designing and administering health and benefits programs for employers.
• Provides risk management and consulting, helping organizations identify, reduce, and finance their risks, including claims assistance and disaster preparedness.
• Runs specialty programs, acting as a program manager in niche verticals.

Where Alliant stands out is specialization. Rather than being a generalist, it has built deep expertise in specific industries: public entities, tribal nations, healthcare, construction, energy, law firms, real estate, and financial institutions, among others. That vertical focus is what the company is best known for. It serves more than 20,000 commercial clients nationwide.

Who owns Alliant insurance, and is it public or private?

Alliant is a private company. It’s not publicly traded, so you can’t buy its stock on an exchange. (That answers the common “Alliant IPO” search: there isn’t one you can invest in as a retail buyer.) Ownership is a mix.

Most of the firm is owned by Alliant’s own management and producers (its brokers). The company emphasizes this as part of its culture. Alongside them, several large private-equity and institutional investors hold significant stakes:

• Stone Point Capital, a financial-services-focused private equity firm, is Alliant’s largest institutional shareholder (since a 2015 investment).
• PSP Investments, a major Canadian pension investment manager, took a stake in a later partnership.
• KKR, the global investment firm, has been an investor since 2012 and remains a significant shareholder.

So the honest answer to “who owns Alliant” is this: primarily its management and producers, backed by private-equity investors led by Stone Point, with PSP and KKR also involved. Ownership stakes among these investors have shifted through several deals over the years. The firm says its management and producers continue to own the majority.

Who bought Alliant, and its ownership history

Since people search “who bought Alliant,” here’s the honest timeline, because it has changed hands among investors more than once. Alliant was founded in 1925, giving it a century of history. In recent decades it moved through several private-equity partnerships. KKR took a major stake in 2012. Stone Point Capital came in as the largest institutional investor in 2015, with KKR staying on. And PSP Investments joined in a later partnership. Throughout, management and producers kept majority ownership.

An important nuance for accuracy: Alliant has not been “bought” outright by a single parent company. It’s a management-and-producer-owned firm with rotating private-equity partners. If you see a headline saying one firm “acquired” Alliant, it almost always refers to one of these stake investments, not a full takeover.

How big is Alliant, and how long has it been around?

Alliant is genuinely one of the giants of US insurance brokerage. By the most-cited industry ranking (Business Insurance’s annual list), Alliant sits around the 5th-largest insurance broker in the US and roughly 5th-largest globally. It’s also ranked the #1 largest privately owned broker in the country. Those rankings have climbed steadily over the past decade, as Alliant grew through organic growth and acquisitions.

By the numbers, Alliant has roughly 14,000 employees and more than 100 offices across the US. It has grown aggressively by acquiring dozens of smaller brokerages. And it’s old: founded in 1925, so it has been around for about a century. That’s a genuine mark of staying power in this industry.

For context, the “big” US and global brokers people ask about, often called the “big 3” of brokerage, are Marsh McLennan, Aon, and Arthur J. Gallagher. Firms like WTW, HUB, and USI are also very large. Alliant runs in that upper tier as one of the largest independent, privately owned players.

Who is the CEO of Alliant Insurance Services?

Based on the most recent company statements, Greg Zimmer is CEO of Alliant. Tom Corbett served for many years as Alliant’s Chairman and CEO and is closely associated with the firm’s modern growth. Leadership titles at large private firms do shift, so if you need the current officer for something important (a contract, due diligence, or press), confirm it on Alliant’s official leadership page or a recent filing rather than relying on any single article, including this one.

Is Alliant insurance any good? (An honest, objective read)

First, a quick clarification, because the search results mix them up: “Alliant” is not the same as “Alliance” insurance. “Alliance” appears in the names of several unrelated insurers and agencies; if you meant a company literally named “Alliance,” that’s a different search. This page is about Alliant Insurance Services, the large brokerage.

Now, “is it good?” Rather than crown it, here’s how to judge a broker like Alliant objectively:

• Scale and stability: As a top-5, century-old broker, Alliant has the market access and financial backing to handle large and complex risks, a real strength for big commercial clients.
• Specialization: Its deep vertical expertise (public entities, tribal nations, healthcare, etc.) is a genuine differentiator if you’re in one of those industries.
• It’s a commercial broker, not a personal insurer: If you’re an individual looking for car or home insurance, Alliant generally isn’t who you’d approach, it’s built for businesses and organizations.
• Judge the service, not just the size: For any broker, the real test is the specific team serving you. Look at their responsiveness, market relationships, and claims advocacy. Check independent reviews (including employee reviews on sites like Glassdoor if you’re considering a job). And for the carriers they place you with, check the carrier’s AM Best rating and NAIC complaint record.

The honest verdict: Alliant is a large, well-established, reputable brokerage that’s especially strong for specialized commercial and public-sector clients. Whether it’s good for you depends on your needs and the specific team you’d work with, exactly what you’d evaluate with any broker.

Quick answers: brokers, contact info, and offices

A few closely related questions come up alongside the main search, so here are direct answers.

Is Alliant a carrier or a broker, in one line? A broker. To settle the “carrier or broker” question for good: a carrier underwrites and pays claims; Alliant arranges your coverage with a carrier and advocates for you. It never becomes your insurer.

Who are the top 5 insurance brokers in the US? By Business Insurance’s ranking, the largest US brokers are led by Marsh McLennan, Aon, and Arthur J. Gallagher (often called the “big 3 insurance brokers”), followed by firms like WTW, HUB, and USI, with Alliant sitting right around the top 5. So when people ask for the “top 5 insurance brokers,” Alliant is in or just outside that group, and it’s the #1 privately owned one.

What is Alliant known for? It’s best known for two things: being the largest privately owned US broker, and its deep specialty-vertical model (public entities, tribal nations, healthcare, and more). That specialization is the reputation the firm has built.

What about Alliant’s phone number, NYC office, and other locations? Alliant runs more than 100 offices nationwide, including a New York City (NYC) presence plus offices in San Diego, Honolulu, and many other metros. For a specific office phone number or address, use the official contact and locations page on alliant.com rather than a third-party listing, since direct-dial numbers and suite locations change and vary by team. I won’t print a number here that might be outdated, the official site is the reliable source.

The Honest Read: how to think about a broker like Alliant

In my years around insurance and out-of-pocket costs, here’s the confusion I see most with big brokerages like Alliant. People assume the broker is their insurer. Then they get frustrated at claim time, when they realize the broker doesn’t pay the claim, the carrier does. Understanding that split changes how you use them. A good broker is your advocate with the carrier, and that advocacy is what you’re paying for, especially on a messy commercial claim. The brokers who earn their keep fight to get a borderline claim paid. That’s worth more than a slightly lower commission.

So here’s the plain verdict.

Alliant is a strong choice if you’re a business, public entity, or organization, especially in one of its specialty verticals, that needs sophisticated coverage and an advocate who knows your industry. Its scale and specialization are real advantages.

Alliant probably isn’t who you need if you’re an individual shopping for personal auto, home, or renters insurance, a large commercial broker isn’t built for that; you’d go to a personal-lines agent or a direct carrier instead.

Whoever you are: remember the broker isn’t the carrier. Ask which carrier your coverage is actually with, check that carrier’s financial strength (AM Best) and complaint record (NAIC), and judge the broker on the responsiveness and claims advocacy of your specific team.

Conclusion

Alliant Insurance Services is one of the largest insurance brokers in the US, a century-old, Irvine-based, privately owned firm ranked around #5 nationally and #1 among privately owned brokers, not an insurance carrier that underwrites policies or pays claims. It’s owned by its management and producers alongside private-equity investors led by Stone Point Capital, with PSP and KKR involved, and it specializes in complex commercial and public-sector coverage. If you’re a business in one of its verticals, it’s a genuinely strong, well-backed option; if you’re an individual buying personal insurance, it’s not built for you. Either way, the key is knowing a broker arranges your coverage, while a carrier is the one who actually insures you.

FAQs

Is Alliant a carrier or a broker?

Alliant is a broker (an insurance brokerage), not a carrier. It arranges and places insurance coverage with actual carriers on behalf of its clients, and provides risk-management and employee-benefits services, but it doesn’t underwrite policies or pay claims itself. The carrier Alliant places you with is your actual insurer and the one who pays claims.

What does Alliant Insurance Services do?

Alliant is an insurance brokerage and consulting firm. It places property & casualty insurance, manages employee benefits programs, and provides risk-management and consulting services, mostly for businesses, public entities, and organizations rather than individuals. It’s known for deep specialization in verticals like public entities, tribal nations, healthcare, construction, energy, and law firms.

Who owns Alliant Insurance Services?

Alliant is a private company owned primarily by its own management and producers, alongside private-equity and institutional investors. Stone Point Capital is its largest institutional shareholder (since 2015), with PSP Investments and KKR also holding significant stakes. Ownership among these investors has shifted through several transactions, but management and producers have retained majority ownership.

Is Alliant Insurance Services public or private?

Alliant is a private company; it isn’t publicly traded, so there’s no stock you can buy on an exchange. This is why “Alliant IPO” searches don’t lead to a public offering for retail investors. It’s owned by management, producers, and private-equity backers led by Stone Point Capital rather than public shareholders.

Who bought Alliant insurance?

Alliant hasn’t been bought outright by a single owner, it’s a management-and-producer-owned firm with rotating private-equity partners. KKR took a major stake in 2012, Stone Point Capital became the largest institutional investor in 2015, and PSP Investments joined later. Headlines about a firm “acquiring” Alliant usually refer to one of these stake investments, not a full takeover.

How long has Alliant insurance been around?

Alliant was founded in 1925, so it has been in business for about a century. That long history, combined with steady growth through organic expansion and acquisitions, has made it one of the largest and most established insurance brokers in the United States.

Is Alliant a big company?

Yes. Alliant is one of the largest insurance brokers in the US, ranked around #5 nationally and globally by Business Insurance, and #1 among privately owned brokers. It has roughly 14,000 employees, more than 100 offices across the country, and serves over 20,000 commercial clients, so it’s a major firm in the brokerage industry.

Who are the top insurance brokers, and where does Alliant rank?

The largest global brokers, often called the “big 3,” are Marsh McLennan, Aon, and Arthur J. Gallagher, with WTW, HUB, USI, and others also very large. Alliant ranks around #5 in the US and globally, and #1 among privately owned US brokers, placing it firmly in the industry’s top tier of independent firms.

Who is the CEO of Alliant Insurance Services?

Based on recent company statements, Greg Zimmer is CEO of Alliant Insurance Services, with Tom Corbett having long served as Chairman and CEO during the firm’s modern growth. Leadership can change at large private firms, so verify the current officer on Alliant’s official leadership page or a recent filing if you need it for something important.

Is Alliant the same as Alliance insurance?

No. “Alliant Insurance Services” is a specific large US brokerage. “Alliance” appears in the names of various unrelated insurers and agencies. If you’re researching a company literally named “Alliance,” that’s a different search. The two are often confused because the names look similar, but they’re not the same company.

Is Alliant insurance any good?

Alliant is a large, well-established, reputable brokerage, especially strong for specialized commercial and public-sector clients thanks to its scale and vertical expertise. Whether it’s good for you depends on your needs and the specific team serving you. Judge it on responsiveness and claims advocacy, and check the AM Best rating of whichever carrier it places you with.

Where is Alliant Insurance Services headquartered?

Alliant is headquartered in Irvine, California (some older sources list Newport Beach, California, from before a move). It operates more than 100 offices across the US, including locations in major cities like New York, San Diego, and Honolulu, so it has a broad national footprint beyond its California base.

Does Alliant sell personal car or home insurance?

Generally no. Alliant is primarily a commercial and specialty broker serving businesses, public entities, and organizations, not a personal-lines agency for individuals. If you’re an individual shopping for car, home, or renters insurance, you’d typically work with a personal-lines agent or buy directly from a carrier rather than a large commercial broker like Alliant.

What is Alliant best known for?

Alliant is best known for deep industry specialization, it builds expert teams around specific verticals like public entities, tribal nations, healthcare, construction, energy, and law firms, rather than being a generalist. It’s also known as the largest privately owned US insurance broker and for growing aggressively through acquisitions of smaller brokerages.

How do I judge whether a broker like Alliant is right for me?

Confirm you need a commercial or specialty broker (Alliant isn’t for personal insurance), then evaluate the specific team’s industry expertise, responsiveness, and claims advocacy. Ask which carriers they’d place you with and check those carriers’ AM Best financial-strength ratings and NAIC complaint records. For employment questions, independent reviews on sites like Glassdoor can help.

About the Author

Md Shahinuzzaman is an insurance and out-of-pocket healthcare cost specialist with 16 years of banking and insurance experience. He writes clear, honest guides for InsuranceGuidances.com to help readers understand who really stands behind their coverage, and how the industry actually works. Every fact here is checked against named sources, including Business Insurance rankings, company announcements, and investor disclosures. Reviewed July 2026.

Sources

National Association of Insurance Commissioners (NAIC), Consumer Information Source (complaint index). https://content.naic.org/consumer

Alliant Insurance Services, official news, ranked #5 US and global broker (Business Insurance 2025). https://alliant.com/news-resources/alliant-insurance-services-ranks-fifth-in-the-us-and-globally-on-business-insurance-largest-brokers-lists/

Stone Point Capital, Alliant company profile (specialty broker, HQ, verticals, acquisitions). https://www.stonepoint.com/company/alliant/

Business Insurance, Alliant private-equity investment from Stone Point (KKR history). https://www.businessinsurance.com/alliant-insurance-services-gets-new-private-equity-investment-from-stone-point-c/

PSP Investments, Alliant strategic partnership (ownership structure, Newport Beach HQ). https://www.investpsp.com/en/news/alliant-forms-strategic-partnership-with-psp-investments/

CB Insights, Alliant Insurance Services profile (founded 1925, Irvine HQ, employees, investors). https://www.cbinsights.com/company/alliant-insurance-services

PitchBook, Alliant Insurance Services company profile (private company, investors, competitors). https://pitchbook.com/profiles/company/10484-02

Private Equity Wire, Alliant secures Stone Point investment (management/producer majority ownership). https://www.privateequitywire.co.uk/alliant-insurance-services-secures-investment-stone-point-capital/

Business Insurance, 100 Largest Brokers of U.S. Business (industry ranking methodology). https://www.businessinsurance.com/

AM Best, financial strength ratings (how to judge a carrier). https://www.ambest.com/