AT A GLANCE

Headway
Sierra
2019
Founded
2023
Chapel Hill, North Carolina
HQ
San Francisco, USA
$226 million
Total Raised
About $1.6 billion
Andrew Adams, Jake Sussman
Founder
Bret Taylor and Clay Bavor
Health Tech
Type
AI
Private ($2.3B valuation)
Status
Private — $15.8B valuation (May 2026)

FUNDING HISTORY

Headway

Seed2019
$3M raised
Series A2021
$26M raised
Series B2022
$70M raised
Series C2023
$125M raised$2.3B val.

Sierra

Seed2024
$110M raised$1.0B val.
Series A2024
$175M raised$4.5B val.
Series B2025
$350M raised$10.0B val.
Venture Round2026
$950M raised$15.8B val.

BUSINESS MODEL

Headway

Headway makes money by taking a percentage of the insurance reimbursement for each session facilitated through the platform. When a patient sees a Headway-credentialed therapist and pays their copay, Headway processes the insurance claim and takes a service fee from the reimbursement before paying the therapist.

The model aligns incentives well. Headway only makes money when therapy sessions actually happen, which means they're incentivized to help therapists see more patients and reduce no-shows.

Therapists make more than they would on their own (because Headway's negotiated rates are often better than individual therapists can get), and patients pay only their insurance copay ($0-$50 typically) instead of full out-of-pocket rates.

Scale creates a data and negotiation advantage. With 40,000+ therapists on the platform, Headway can negotiate better reimbursement rates with insurers.

More therapists attract more patients. More patients justify better rates.

The flywheel spins.

Sierra

Companies pay Sierra to run their customer service with AI agents instead of hiring rooms full of humans. The agent talks to your customers over chat.

It answers questions. It processes returns.

It updates subscriptions. Here is the clever part.

Sierra charges based on outcomes, not seats. Brands pay when the AI actually resolves a problem, not just for having the software installed.

That pricing is unusual. Most software charges a flat monthly fee no matter what.

Sierra only gets paid when the bot does the job.

HOW THEY STARTED

Headway

Andrew Adams and Jake Sussman founded Headway in 2019 after watching people in their lives struggle to access affordable mental healthcare. The problem was specific and structural: most therapists operate as solo practitioners who don't accept insurance.

Not because they don't want to — because the process of getting credentialed with insurance companies, submitting claims, and chasing reimbursements is so bureaucratically painful that most therapists give up and go cash-only.

The result is a two-tier mental healthcare system. People with money pay $150-$300 per session out of pocket.

People without money either can't afford therapy or wait months for the few in-network providers available. Meanwhile, therapists who only accept cash are leaving money on the table — insurance pays reliably once the system works, and the patient pool is vastly larger.

Headway's solution was to build the infrastructure layer that makes insurance billing painless for therapists. They handle credentialing (getting the therapist accepted into insurance networks), claims submission, payment processing, and compliance — all the administrative work that therapists hate.

The therapist shows up, does therapy, and Headway handles everything else.

Sierra

Bret Taylor had already done the impossible twice. He co-created Google Maps.

He later became co-CEO of Salesforce, chaired Twitter's board during the messy Elon Musk takeover, and became chairman of OpenAI in late 2023. Clay Bavor spent 18 years at Google, most recently running its Labs group.

The two friends left their big jobs in 2023 to build something together. They picked customer service on purpose.

It is the least glamorous corner of software. Their logic was simple.

Companies hate their support costs. Customers hate waiting on hold.

AI that actually resolves problems could fix both sides at once. They launched Sierra in February 2024 with $110 million from Sequoia and Benchmark.

HOW THEY GREW

Headway

Headway grew by solving the supply-side problem first. If you can get enough therapists on the platform and credentialed with insurance, patients will come because affordable therapy is in massive demand.

They recruited therapists with a compelling pitch: "keep doing therapy, we'll handle the business side."

Insurance partnerships were the growth unlock. Headway partnered with major insurance companies (Aetna, Cigna, United Healthcare, Anthem) to become an authorized credentialing partner.

This meant Headway could get therapists in-network faster and with less friction than the traditional process.

The mental health destigmatization wave amplified demand. Post-COVID, demand for therapy skyrocketed.

The conversation around mental health became mainstream. Headway was positioned perfectly to absorb that demand by connecting patients with affordable, insurance-covered therapists.

Sierra

Sierra went straight for big brands, not tiny startups. SoFi, Ramp, ADT, Sonos and Brex signed up early.

By 2026 it said more than 40% of the Fortune 50 were customers. The trick was trust.

Enterprises are terrified of an AI bot going rogue and insulting a customer. So Sierra built guardrails and let each company control exactly how the agent behaves.

Bret Taylor's contacts did the rest. When the chairman of OpenAI calls a Fortune 500 CEO, they pick up.

Sierra hit $100 million in annual recurring revenue in November 2025, seven quarters after launch, and $150 million by February 2026. In April 2026 it launched Ghostwriter, which builds and deploys a new agent from a plain-English description.

THE HARD PART

Headway

Therapist retention is a challenge. Solo practitioners are independent by nature, and some leave the platform once they've built a full patient roster through Headway.

The platform needs to continuously demonstrate value beyond initial credentialing to keep therapists from going direct.

Insurance reimbursement rates are notoriously low. Therapists who accept insurance often earn 30-50% less per session than cash-pay rates.

While Headway negotiates better rates than individual therapists typically get, the fundamental economics of insurance-based mental healthcare remain challenging.

Regulatory complexity varies by state. Each state has different licensing requirements, insurance regulations, and telehealth rules.

Expanding to all 50 states means navigating 50 different regulatory frameworks, each with their own credentialing requirements and compliance standards.

Sierra

Everyone is building AI customer service agents right now. Decagon has raised at a multi-billion valuation.

Salesforce, ServiceNow and Intercom all shipped their own agents. Sierra is not the cheap option.

It sells premium AI to giant companies that move slowly. The bigger risk sits underneath the product.

Sierra does not make its own AI models. It rents them from providers like OpenAI and Anthropic.

If those model makers decide to compete directly, Sierra's edge gets thin fast, and its co-founder chairing one of them only makes that question louder. A $15.8 billion valuation on roughly $150 million in revenue leaves almost no room for a stumble.

THE PRODUCTS

Headway

Headway Provider Platform — the core system where therapists manage their practice: scheduling, credentialing, claims submission, payment tracking, and patient communications. Headway Patient Matching — a directory and matching service that connects patients with in-network therapists based on insurance, location, specialty, and availability.

Insurance Credentialing Service — Headway handles the months-long process of getting therapists accepted into insurance networks, reducing what typically takes 6-12 months to weeks. Claims and Billing Engine — automated insurance claims submission and tracking that eliminates the paperwork therapists dread.

Practice Management Tools — scheduling, intake forms, session notes, and telehealth capabilities integrated into one platform.

Sierra

The core product is the Sierra AI agent. It is a branded customer service bot that companies deploy on their website, app, and phone lines.

It handles the boring stuff. Order tracking.

Refunds. Password resets.

Account changes. Sierra also built its own tools to test and monitor these agents so they do not make things up.

In 2024 the company added a voice version that talks to customers on the phone. In April 2026 it added Ghostwriter, a tool that builds and deploys a new agent from a plain-English description.

The whole pitch is one AI agent that carries your brand's name and never sleeps.

WHO BACKED THEM

Headway

Andreessen Horowitz led the Series C at a $2.3 billion valuation. Accel and Thrive Capital invested in earlier rounds.

GV (Google Ventures) and Spark Capital also participated. The company has raised approximately $226 million total.

Sierra

Sequoia Capital and Benchmark wrote the first checks at launch in February 2024, $110 million between them. Greenoaks Capital then led both the $175 million round in 2024 and the $350 million round in September 2025.

In May 2026 Tiger Global and Google's GV led a $950 million round at a $15.8 billion valuation, with Benchmark, Sequoia and Greenoaks back in. That takes total funding to about $1.6 billion.

That is partly the product and partly Bret Taylor. Investors bet on founders who have already built billion-dollar things.

MORE COMPARISONS