AssetMark vs SEI 2026: Costs, Custody, and Buyer Fit

Choose the operating model before the investment menu

AssetMark deserves your shortlist when you want a curated investment platform with advisor support; SEI deserves it when connected custody, technology, and investments are central to your operating model. Neither description establishes a winner for your firm. The deciding questions are which accounts you can support, which responsibilities you retain, and what the complete arrangement costs.

A turnkey asset management program, or TAMP, combines outsourced investment management and associated administration so advisors can focus on advice and client relationships.

TL;DR: Favor AssetMark for a supported investment-outsourcing approach, and favor SEI for a custody-centered operating approach. Choose only after comparing the same representative households, custody requirements, and written fee components.

Ownership matters. AssetMark Financial Holdings is privately owned by GTCR, and AssetMark reports SEC registration since 1999, according to AssetMark. Older comparisons that describe a different controlling owner need updating.

SEI Investments Company remains publicly traded under SEIC. Technology and operations: approximately 57% of revenue according to SEC (2025). That is a company-wide revenue mix, not an advisor-platform adoption rate; it helps explain why SEI should be evaluated as more than an investment menu.

Key Takeaways

• AssetMark and SEI overlap in investment outsourcing, but your custody and service arrangements determine how much operational change each requires.

• AssetMark suits buyers who value a curated strategy selection and structured investment administration; confirm the specific managers and account arrangements you need.

• SEI suits buyers evaluating custody, advisor technology, and investment solutions together; verify which services your proposal includes.

• Treat both configured offerings as Quote-based for total-cost comparison. A strategy fee or wrap disclosure alone does not establish the complete household cost.

• Make permissions, data exports, exception ownership, and exit procedures acceptance conditions. A successful portfolio presentation does not prove that your surrounding workflows will function.

Who this is for

This guide is for an advisory firm choosing an investment-outsourcing provider, replacing an existing TAMP, or reconsidering whether its custody and technology arrangement supports its investment process. It is especially relevant when investment selection looks straightforward but account opening, reporting, billing, or migration responsibilities remain unclear.

It is less useful for an individual investor choosing a fund. The relevant decision here belongs to the advisory business and its client-service model, with appropriate investment, operational, and compliance review.

Red flags: your affiliation cannot approve the proposed arrangement; required account types or investment restrictions are unsupported; the provider cannot supply an acceptable data-access or exit arrangement.

Resolve those disqualifiers before scoring softer preferences. A provider that looks attractive on reporting or investment choice can still be unsuitable if the firm cannot use it under its actual operating constraints.

How we evaluated the buyer trade-offs

We compared public service descriptions and disclosures, then separated those facts from our buyer analysis. We did not conduct platform testing, obtain negotiated proposals, or measure implementation outcomes. The weights below are editorial priorities for a buyer worksheet, not vendor performance statistics.

Score each criterion from 1 to 5 using evidence supplied for your firm. Calculate its weighted contribution as score divided by 5, multiplied by the weight. Do not assign an unknown capability an average score: leave it unresolved and request evidence.

These weights total 100% by design. Adjust them before requesting proposals if your nonnegotiable constraint differs. Keep disqualifiers outside the weighted score so a favorable presentation cannot compensate for an unsupported account.

For an operational analogy, our campaign exception-monitoring recipe shows why a detected issue still needs an owner and next action. It supplies process context, not evidence about either TAMP.

Normalize capabilities before comparing presentations

The matrix below describes the public positioning of each provider. Availability, permissions, implementation scope, and commercial terms must still be confirmed for your arrangement; a listed capability is not a promise that every account qualifies.

Avoid interpreting open architecture as unrestricted access to every manager, custodian, or integration. Ask each provider to demonstrate your actual combination. Similarly, distinguish native functions from separately contracted services and work your staff must perform.

The important comparison is the resulting operating model: who supplies the records, who executes approved changes, who checks exceptions, and who remains accountable to the client.

AssetMark: examine the investment-outsourcing fit

AssetMark is a strong candidate when the firm wants to select among curated investment approaches while retaining ownership of client advice. Its platform includes proprietary and third-party strategies, account administration, and tax-management options. The advisor still has responsibilities for recommending a suitable strategy and monitoring its appropriateness; outsourcing does not erase that role.

Its platform brochure, effective December 15, 2025, describes those responsibilities and separate fee components, according to AssetMark. Use that primary disclosure to distinguish investment management from the obligations your advisory firm retains.

Best fit: a firm that values an investment platform and supporting services, with a willingness to operate within the documented account and strategy arrangements. The practical advantage to evaluate is whether the offering reduces the specific administrative work your staff currently performs.

Limitations: a broad menu does not prove that your preferred strategy, custody arrangement, household restrictions, or data interface is available. Do not choose on the assumption that surrounding CRM or reporting work will disappear. Require the proposed configuration to demonstrate those handoffs.

Implementation: prepare an account inventory, current holdings, registrations, restrictions, and unresolved transfer issues. Ask who will map existing positions, identify assets that cannot transfer as intended, and coordinate client paperwork. Review tax-sensitive transition decisions with the appropriate professionals before authorizing changes.

A meaningful disqualifier is an arrangement that cannot support a required registration or investment restriction. Another is an unacceptable gap between the records you need and the information you are permitted to export. These are buyer acceptance conditions, not claims that AssetMark lacks those capabilities generally.

SEI: examine the connected operating foundation

SEI is a strong candidate when the firm wants to consider custody, advisor technology, and investment solutions as a connected arrangement. Its advisor offering is broader than selecting model portfolios, so the evaluation should include operational responsibilities as well as investment preferences.

Reported custody assets: $1.2 trillion according to SEI (December 31, 2025). This is the custody figure displayed on its advisor overview, not the assets of your proposed TAMP program or evidence of investment performance. The same page identifies connected technology, custody, investment solutions, and business support.

Best fit: a firm that wants to assess its custody and investment infrastructure together and is prepared to document how its existing tools will connect. Ask which parts you can adopt independently and which operational dependencies the recommended arrangement creates.

Limitations: connected services do not automatically remove specialist tools or staff responsibilities. A firm that must preserve a particular external custody arrangement should get written confirmation of the exact supported scope. Do not assume that a broad corporate service offering is included in your advisor proposal.

Implementation: review account-opening requirements, investment discretion, reporting responsibilities, existing CRM processes, and proposed data access together. Have the provider demonstrate the intended account lifecycle using representative cases rather than an idealized household.

Reject the proposed arrangement if it requires an unacceptable custody change or cannot support your required investment process. Conversely, do not dismiss SEI simply because you already have specialist tools: the relevant question is whether the configured combination supports your operating model with clear responsibilities.

Pricing and TCO: compare the same household specification

Pricing checked October 12, 2026.

Use Quote-based for the total configured offering from each provider. AssetMark publishes strategy-specific fee disclosures, so Quote-based does not mean that no fee information exists. It means a generic vendor rate would not capture the complete arrangement. SEI likewise requires a proposal tied to the services and investments selected.

SEI directs readers to its adviser or wrap brochure for fee disclosure and cautions against assuming particular tax outcomes, according to SEI. No vendor price is estimated here.

Give both providers the same account list, investment preferences, service requirements, and assumptions about retained software. Ask them to identify exclusions explicitly. A comparison becomes unreliable when a comprehensive arrangement is placed beside a narrower investment-management quote.

The independent directory lists an advisor-solutions brochure dated September 1, 2026, and a managed-account wrap brochure dated August 31, 2026, according to AdvisorCheck. Request the applicable current documents from SEI; a directory listing identifies documents but does not establish your negotiated terms.

Recurring administration is a separate cost problem from investment selection. Our membership-administration guide provides a cross-industry analogy for distinguishing recurring service delivery from billing administration. It does not supply financial-platform pricing or suitability evidence.

Read strategic expansion as a diligence question

Announced Stratos stake: 57.5% according to RIABiz (2025). That report described SEI's planned investment and both firms' efforts to expand their RIA presence. It is historical strategy context, not a claim that the announcement itself completed the transaction.

For a buyer, expansion raises practical questions rather than proving better service. Ask whether your assigned team, support channels, contractual services, or platform roadmap will change. Obtain commitments that apply to your firm instead of relying on corporate ambition.

Likewise, ownership structure does not establish investment quality. Evaluate conflicts, service accountability, and the portability of your operating records directly.

Close the operational gaps around either TAMP

The work outside investment management often determines whether a change feels manageable: gathering paperwork, matching CRM households to investment accounts, assigning exceptions, and preserving evidence of review. First ask whether the provider or an existing tool already covers those tasks adequately.

A proposed US Tech Automations workflow could start when an approved account export arrives in a restricted location. It would validate the file, match stable account identifiers to authorized CRM records, and create an internal exception queue for missing or inconsistent information. Its output would be a reconciliation summary with source timestamps and assigned owners. Prerequisites include permitted exports or documented API access, an agreed schema, access controls, and retention rules; operations staff would review unmatched records before any downstream update.

Illustrative scenario: suppose a transition covers 12 households with 3 accounts each, giving 12 × 3 = 36 accounts. Comparing those accounts at 2 checkpoints produces 36 × 2 = 72 comparisons; if 1 comparison needs review, 72 − 1 = 71 match and 1 enters the exception queue. Salesforce documents Account.Name in relationship exports, according to Salesforce. Use that field for display context and stable record identifiers for matching. These counts are hypothetical inputs and arithmetic, not customer results or vendor capacity claims; a reviewer resolves the exception before migration status changes.

A second proposed US Tech Automations workflow could begin when an approved account-status file changes. It would compare the new status with the last accepted version, suppress duplicate processing, and prepare an internal task for the responsible team. The output would include the status change, source reference, outstanding dependency, and review history. It requires authorized status data, stable identifiers, CRM write permission if tasks are created there, and a designated escalation owner. Staff would approve client communications and review any action affecting investment or custody records.

Technical discovery must distinguish interface metadata from actual account data. Salesforce's search-layout resource supports requests for up to 100 objects, according to Salesforce. That limit concerns layout metadata, not investment accounts or TAMP synchronization. Validate the actual data interface and permissions separately.

Zapier, Make, and n8n can support run histories, retries, error branches, and audit evidence when configured. An in-house build can do so too. The buyer must design and own observability, idempotency, escalation, access controls, and maintenance. A proposed orchestration design could instead make those requirements explicit in its mapping rules, exception states, approval steps, and operating documentation, subject to the same access prerequisites and human review.

Our agency workflow comparison offers another process analogy: producing an output and approving its use are separate responsibilities. It is not evidence of financial-services implementation.

Define acceptance before moving client accounts

The following is a proposed acceptance worksheet using hypothetical counts from the illustrative scenario. These are buyer-designed checks, not published platform limits or measured performance.

Use representative authorized data and retain the original input alongside the review output. Add your difficult cases, such as restricted holdings, ambiguous household mappings, and incomplete paperwork. Agreement on the expected behavior matters more than the illustrative counts.

Use this decision checklist before signing:

• Confirm custody eligibility and required account registrations.

• Demonstrate the investment approaches and restrictions you need.

• Compare complete household costs using the same assumptions.

• Approve usable data access and record-retention arrangements.

• Assign migration, exception, maintenance, and departure responsibilities.

Keep a departure procedure alongside the onboarding plan. If a requirement remains unknown, resolve it before relying on it in production.

Questions buyers should settle before choosing

Is AssetMark or SEI the better TAMP?

The better fit is the provider whose documented operating arrangement meets your custody, investment, and service requirements.

AssetMark deserves attention for supported investment outsourcing; SEI deserves attention for connected custody, technology, and investments. Compare the proposed configuration, not an abstract vendor reputation, and let disqualifiers override weighted preferences.

Which provider is cheaper?

The cheaper provider cannot be identified without comparable written proposals.

Compare the same households, strategies, custody scope, retained software, and staff responsibilities. Confirm underlying investment expenses and exclusions separately. A narrower quote can look less expensive while leaving more operational work with your firm.

Do I have to change custodians?

A custody change depends on the specific arrangement offered and your existing accounts.

Ask for written confirmation covering registrations, asset eligibility, transfer procedures, and any supported external arrangements. Do not treat a marketing description as approval for the exact custody combination your firm needs.

Does outsourcing remove our investment responsibilities?

Outsourcing transfers the contracted tasks while your firm retains its applicable advisory responsibilities.

Document who recommends strategies, checks restrictions, monitors client circumstances, and approves changes. Review the applicable agreements and disclosures with the appropriate professionals. A responsibility map is more useful than assuming that the word turnkey covers everything.

Can we keep our CRM and build the workflows ourselves?

You can consider retaining your CRM if the proposed arrangement supplies authorized, usable data access.

Evaluate existing functions first, then compare a configurable automation tool with an in-house build. Require stable identifiers, duplicate handling, failure visibility, restricted access, and a named maintenance owner. Integration should be demonstrated with your approved records before adoption.

When NOT to use US Tech Automations?

Use a simpler existing tool when its native workflow already covers the task with adequate controls.

An existing TAMP report may be sufficient for routine reconciliation; an approved CRM rule may handle straightforward task routing; a manually reviewed export may suit an infrequent transition. Additional orchestration is difficult to justify when access is unavailable or the firm cannot assign exception and maintenance ownership.

Make the decision on the arrangement you can operate

Choose AssetMark when its investment platform and supporting services fit your account requirements. Choose SEI when its connected custody, technology, and investment approach fits the operating foundation you want. Require comparable proposals and evidence for the unresolved handoffs before committing.

If administration still spans disconnected systems, see how US Tech Automations could configure the review workflow around authorized exports, internal tasks, and human approvals. Define that workflow after choosing the investment and custody arrangement it must support.