Automatic Investment Plan (AIP)
The Formal Definition
A scheduled broker account feature that automatically executes recurring bank debits (via ACH or SEPA) to purchase designated dollar amounts of whole or fractional shares of ETFs, stocks, or mutual funds at pre-scheduled intervals.
AIP Effective Cost = ∑ [Recurring Debit_t / Market Spot Price_t] × (1 + Hidden Spread Markup)
Cole Barrett's Reality Check
The Unvarnished Bottom Line"Automatic investment plans are the holy grail of personal finance habit-building, but they are also a sneaky profit center for neobrokers. Watch out for 'zero-fee savings plans' that execute your recurring orders at 10:30 AM through internal wholesale market makers who widen the spread when you aren't looking."
Interactive Simulator: Test the Math
Real-World Example: Scenario Breakdown
Examining the real numbers for: An investor automating a $500 monthly recurring investment into a broad market index ETF over 10 years ($60,000 total invested)
| Execution Metric | Lit-Market Low-Cost AIP | Neobroker Savings Plan with Internal Execution |
|---|---|---|
| Fee / Rate | $0 automated savings plan fee | $0 advertised execution ticket |
| Spread / Buffer | Order executed during peak market liquidity with direct exchange routing and tight 1-cent NBBO spreads | Broker bundled all AIP orders into an illiquid morning window routed exclusively through an off-exchange partner |
| Execution / Status | Captured the exact un-shaded index price on the scheduled execution date | Fills suffered an average 0.25% spread markup above the consolidated tape price on every monthly run |
| Total Cost / Result | Maximized passive wealth accumulation without execution drag | Suffered hidden execution taxes on every recurring transfer |
How Brokers Weaponize This Term
If your broker offers free automated investment plans, check what time of day your orders execute. If they run in the pre-market or within the first 15 minutes of the market open (9:30–9:45 AM EST) when spreads are naturally widest, you are paying a hidden execution tax on every purchase.
Broker Evaluation Matrix
Cole Approves
Trade Republic: Popularized commission-free recurring ETF and stock savings plans across Europe with complete automated SEPA recurring functionality.
Read Audit →Cole Flags / Avoids
High-Fee Legacy Mutual Fund Desks: Charges upfront transactional booking fees or ongoing management wrap surcharges on automated monthly investment contributions.
View Trap Details →Frequently Asked Questions
Can I set up an AIP for fractional shares?
Yes. Most modern brokers support fractional share investing on automated plans, allowing you to split a $100 recurring payment across multiple different high-priced stocks.
What happens if my bank account doesn't have enough funds on AIP execution day?
The transfer will fail, and your broker will typically hit you with a painful $20 to $35 Returned ACH / Insufficient Funds penalty fee. Always set your AIP execution date 2 days after your paycheck clears.