Adhesion Wealth is working with Fidelity Investments to let more registered investment advisors commission custom model portfolios built around their own investment preferences.
The move adds to a string of 2026 launches that treat tailored models as the next contest for RIA assets.
The unified managed account platform, which AssetMark acquired from Vestmark in 2022, has announced the launch of a custom model solutions offering that pairs Fidelity's portfolio construction and manager research with Adhesion's trading, rebalancing and tax-management technology.
The Charlotte, N.C.-based firm said advisors can use it without paying Adhesion's platform fee or the fee for its Tax Management Services, which it launched in July.
UMAs allow advisors to hold several types of investment strategies – including mutual funds, exchange-traded funds and separately managed accounts – in separate "sleeves" within a single client account. Running several sleeves across many accounts is operationally heavy, which is why Adhesion and other TAMP providers have rolled out offerings to take that work off advisors' desks.
"RIAs consistently tell us they want to deliver investment experiences that reflect their own preferences without having to build and maintain all the infrastructure and staffing required to manage customized portfolios at scale," said Phill Rogerson, senior vice president and head of RIA at Adhesion Wealth.
Under the arrangement, an advisory firm works with Fidelity to design portfolios that reflect its preferred managers, vehicles, asset allocation and rebalancing approach. The models are open architecture, so they can hold strategies from managers other than Fidelity across mutual funds, ETFs and SMAs. Each model carries a firm-specific product name and client-facing marketing materials.
Adhesion handles implementation, which covers multi-sleeve portfolios, ongoing trades, and daily tax optimization and tax-aware transitions through its Tax Management Services, which launched in July.
The offering, which according to Rogerson "gives advisors a way to deliver tailored portfolios to more clients while addressing greater portfolio sophistication," targets a familiar dilemma for independent firms. Off-the-shelf third-party models may not match a firm's investment views, but proprietary portfolios built in-house require staff and infrastructure that many RIAs don't have.
Fidelity has also added 14 models to Adhesion Essentials, the platform's lineup of ready-made portfolios with no platform fee. Adhesion said it plans to launch a Manager Research Center and expanded direct indexing later this year, as well as add more asset managers to the custom lineup.
Adhesion is launching its latest offering into a not-so-blue ocean of options. In August, Vanguard launched customizable model portfolios for advisors, which are available through Vestmark, SS&C Black Diamond and Orion. Earlier this year, T. Rowe Price and Vestmark teamed up on custom models that RIAs can use without a platform fee.
The money is following. Assets in third-party model portfolios reached $943 billion as of March 31, 2026, up 46% from a year earlier, according to Morningstar's US Model Portfolio Landscape report. Custom models accounted for $258 billion of that total, up 40%.
New research from Cerulli Associates suggests model portfolio providers are building beyond basic asset allocation. Based on that survey research, 68% of model providers ranked custom models for broker-dealer and enterprise RIA home offices as a top-three product development priority, up slightly from 65% in 2025.
Notably, the share of providers ranking the addition of semi-liquid and illiquid alternatives, such as interval funds, among their top three priorities rose to 57% from 40%. Half the providers cited adding more investment vehicle wrappers, including SMAs, up from a third the prior year. In line with that trend, Fidelity itself has rolled out private markets model portfolios for wealth managers.
Among providers focused on alternatives, more than half aim their models at least partly at every client tier. That runs the gamut from the mass market, with under $100,000 in investable assets, to the wealth market, with $5 million to $10 million.
Tax management has shifted from a product goal to an expected feature. More than 80% of model issuers told Cerulli that tax optimization for taxable accounts is an important service and support initiative.
"Model providers see the importance of integrating tax optimization strategies for all client segments," said Kevin Lyons, associate director of product development at Cerulli. "Among those prioritizing this initiative, more than 40% report at least a minor focus on mass-market, middle-market, and mass-affluent clients, while close to 40% are focused on higher-wealth-tier clients.
"Higher-net-worth clients are particularly sensitive to tax efficiency, and solutions delivered through models offer an effective way for advisors to implement tax overlay strategies at scale," Lyons added.
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