The unified infrastructure layer for financial services.
Post-trade clearing, brokerage-as-a-service, portfolio management, and retirement plan administration — four historically separate vendor categories, unified on a single modern API. Replace four legacy vendor relationships with one contract.
curl -X POST https://api.interposehq.com/v1/orders \
-H "Authorization: Bearer $TOKEN" \
-d '{
"account_id": "acct_01HV4Y2K3M5N8P9QR2ST4UVWXY",
"security": { "type": "ticker", "value": "AAPL" },
"side": "BUY",
"type": "LIMIT",
"quantity": "10.00000000",
"limit_price": "185.5000",
"currency": "USD"
}'{ "order_id": "ord_01HV4...", "status": "SUBMITTED" } // < 50ms1 API key
Unlocks all four pillars
CloudEvents 1.0
Every state change, every pillar
WebSocket
Real-time streams — no polling
60 days
From sandbox to production
Integrates with the financial ecosystem you already rely on
DTCC / NSCC
Clearing & Settlement
FIX 4.2 / 4.4
Order Routing Protocol
ACH / RTP
Bank Connectivity
KYC / AML
Identity & Compliance
ERISA / DOL
Retirement Compliance
OAuth 2.0 + PKCE
Authentication
CloudEvents 1.0
Async Event Schema
OpenAPI 3.1
API Specification
Four Pillars, One Platform
Every layer of the financial stack — finally unified.
Use any pillar independently or all four together. No hidden coupling, no surprise integration tax.
Portfolio Management
The RIA platform advisors actually want to use.
Incumbent platforms charge 6–7 bps on AUM and run on legacy infrastructure. Interpose delivers GIPS-compliant TWR/MWR performance, model-based rebalancing, AUM billing, and a white-label advisor portal — all on the same unified data model and event stream.
- Direct indexing — clients own individual securities, not fund shares
- Tax-aware rebalancing with pre-trade gain/loss impact calculation
- Household-level rebalancing across taxable, IRA, and retirement accounts
- Alternative investments native support (PE, hedge funds, real assets)
- TWR (Modified Dietz) + MWR (IRR) — GIPS compliant
- Multi-custodian aggregation on a unified data model
- Real-time AUM WebSocket stream via shared event bus
Brokerage-as-a-Service
Full-stack brokerage on a single API.
Most BaaS providers hand off clearing to a third party and give you a polling API. Interpose exposes every account, order, position, and compliance event through a unified REST + WebSocket API — account opening through settlement, one data model.
- Unified account model: individual, joint, IRA, custodial
- Orders, positions, and balances via REST and WebSocket
- KYC/AML automated decision — no manual review queue
- Fractional shares at 8 decimal place precision
- Synchronous compliance checks on every order (PDT, Reg-T, SHO, OFAC)
- ACH bank funding
- CloudEvents 1.0 on every account and order state change
Post-Trade
Clearing and settlement on a modern API — no mainframe required.
Incumbent clearinghouses run on COBOL mainframes and expose no real-time API. Interpose wraps DTCC/NSCC clearing, reconciliation, and corporate actions in a cloud-native event-sourced layer — every settlement state change emits a CloudEvent.
- DTCC/NSCC clearing via Continuous Net Settlement
- Every settlement event streamed via WebSocket and Kafka
- Real-time reconciliation breaks — event-driven, not overnight batch
- Corporate actions: dividends, splits, mergers, rights
- T+0 path via USDC/USDT stablecoin settlement
- SEC Rule 17a-4 WORM audit trail (S3 Object Lock)
- CAT reporting built-in
Retirement Plan Administration
Retirement infrastructure that has an actual API.
Legacy TPA providers run nightly batch jobs and offer no API access. Interpose exposes plan data, contribution events, and participant state through the same unified API and event bus as every other pillar — real-time, not overnight.
- Plans, participants, and contributions via REST and WebSocket
- 401(k), 403(b), 457(b), SEP, SIMPLE, DB plans
- On-demand ADP/ACP nondiscrimination testing via API
- SECURE 2.0 RMD logic with automated RBD tracking
- §402(g) / §415(c) IRS limit enforcement
- DOL Form 5500 filing support
- CloudEvents 1.0 on every contribution and distribution event
Portfolio Management · Advanced Capabilities
Institutional-grade PM — built for the modern RIA.
Capabilities that legacy PM platforms charge extra for — or don't support at all — are first-class features in Interpose PM, on the same unified data model and event stream as every other pillar.
Direct Indexing
Clients own the underlying securities directly — not a fund share. Interpose constructs and maintains custom index portfolios at the individual stock level, enabling personalized factor tilts, ESG exclusions, and position-level tax-loss harvesting at scale. Fractional share precision handled natively via the BaaS pillar.
Tax-Aware Rebalancing
Every rebalancing decision is evaluated against the tax ledger before execution. Short vs. long-term lot classification, wash-sale window detection, and realized gain budgets are computed pre-trade — not discovered post-settlement. Advisors set gain thresholds per account; the engine respects them automatically.
Household-Level Rebalancing
Rebalance across all accounts in a household — taxable brokerage, Roth IRA, traditional IRA, 401(k) — as a single coordinated unit. Asset location strategy is assigned per account type automatically: tax-inefficient assets (bonds, REITs) placed in tax-deferred accounts; growth equity in taxable. One rebalance order, household-optimal execution.
Alternative Investment Native Support
Private equity, hedge funds, real assets, and interval funds modeled natively alongside liquid securities — not as a workaround. NAV-based valuation with configurable update frequency, illiquidity constraints that block over-allocation, and commitment schedule tracking. Alternatives appear in performance reports and household views without manual data entry.
Competitive Landscape
No one else does all four.
Legacy vendors own post-trade. BaaS platforms own custody. PM platforms own portfolio management. Nobody owns all four — until now.
| Capability | You are hereInterpose | Legacy Post-Trade Vendors | BaaS-Only Platforms | PM-Only Platforms |
|---|---|---|---|---|
| Post-Trade Clearing (as API) | ||||
| Brokerage Custody (BaaS API) | ||||
| Portfolio Management | ||||
| Retirement Plan Admin (TPA) | ||||
| API-first architecture | ||||
| Unified single contract | ||||
| Real-time WebSocket streams | ||||
| Cloud-native (no mainframe) | ||||
| T+0 / stablecoin settlement | ||||
| Fractional shares | ||||
| Multi-custodian PM | ||||
| AI Back-Office Agents |
Who It's For
Four audiences. One platform.
Use any pillar independently. Each customer type gets exactly what it needs — no vendor sprawl, no integration tax.
Fintech Builders
Embed a full brokerage in 60 days.
Your users want to invest. You need fractional shares, real-time positions, and compliance — but not three vendors, nine months of integration work, and a custom integration layer your team maintains forever.
- One API key — account opening through settlement
- KYC auto-decision — no manual review queue
- Synchronous compliance checks on every order, zero extra code
- WebSocket positions stream — polling is never required
RIAs & Wealth Managers
Replace 3 vendors with 1 contract.
Below $5B AUM, major custodians won't prioritize your support ticket. You're reconciling data across three systems and rebuilding performance reports by hand every quarter.
- Unified data model across custody, portfolio, and billing
- GIPS-compliant TWR + MWR in every report
- Tax-loss harvesting with wash-sale constraint checking
- White-label advisor portal — your brand, your URL
Broker-Dealers
Modern clearing infrastructure with a real API.
DTCC's T+1 mandate is live. Your clearing runs on legacy infrastructure — no real-time API, no event stream, no path to T+0, and reconciliation breaks discovered the morning after.
- Every settlement state change emits a CloudEvent — no polling
- Real-time reconciliation breaks — not overnight batch
- T+0 path via stablecoin settlement
- CAT reporting built-in, not bolted on
Plan Sponsors
Retirement administration with real-time visibility.
Legacy TPA providers run nightly batch jobs on contribution data, offer year-end-only nondiscrimination testing, and provide no API access or real-time event stream.
- Plan and participant data via REST and WebSocket — no batch export
- On-demand ADP/ACP testing — not just at year-end
- SECURE 2.0 RMD tracking and IRS limit enforcement built in
- CloudEvents on every contribution and distribution
How It Works
Built for developers first.
One API, four pillars
A single HMAC-signed API key gives you access to all four pillars. Use just BaaS for embedded brokerage, just Post-Trade for clearing, PM on top of an existing custodian, or TPA for retirement plan administration.
Event-sourced by default
Every state change emits a CloudEvent 1.0 on Kafka. WebSocket streams push those events to your app in real time. Positions are always derived from the immutable transaction ledger — never overwritten.
Compliance as code
Reg-T, PDT, Reg SHO, OFAC, and AML rules are expressed as executable policy, checked synchronously on every order. Rejections include machine-readable check names, not just HTTP 422.
60 days to production
Sandbox mirrors production exactly. OAuth 2.0 + PKCE for portal apps, HMAC-SHA256 for server-to-server. DTCC UAT environment included. Typical fintech goes live in 60 days, not 9 months.
AI Back-Office
11 AI agents. Zero operations headcount.
Every pillar ships with purpose-built AI agents that automate the workflows your ops team handles manually today. Configurable autonomy levels — fully automated or human-in-the-loop approval workflows.
Settlement Monitor
Post-TradeWatches DTCC feeds in real time and escalates break alerts before end-of-day cutoff — no overnight batch surprises.
Recon Analyst
Post-TradeFlags position mismatches between internal ledger and custodian data the moment they appear, not the morning after.
Compliance Checker
BaaSPre-trade Reg-T, PDT, Reg SHO, and OFAC screening synchronously on every order with machine-readable rejection codes.
Corporate Action Processor
BaaSAutomatically applies dividends, stock splits, and rights elections across all accounts — no ops team intervention required.
Portfolio Drift Monitor
Portfolio MgmtDetects accounts outside rebalancing band thresholds and queues drift-triggered rebalancing events for advisor approval.
ADP / ACP Tester
RetirementRuns on-demand nondiscrimination testing at any point in the plan year — not just at year-end like legacy TPA providers.
For Developers
OpenAPI 3.1 specs.
Sandbox on day one.
Every endpoint is documented with request/response examples. Specs are machine-readable — generate your client SDK in any language. The sandbox mirrors production exactly; no mock data, no surprises.
Early Access
Start building on Interpose.
We're onboarding early design partners. Fintechs, RIAs, and broker-dealers get sandbox access, dedicated support, and input on the roadmap.
api@interposehq.com · Typically responds within 24h