How it works
Cash drag is the return your portfolio forgoes because a slice sits in low-yield cash while the rest chases market returns. The arithmetic is disarmingly simple — a 15% sleeve earning 4% inside a portfolio otherwise assuming 7% blends the whole account's return down to 6.35%, a 65-basis-point haircut — but the consequences compound: on $250,000 over fifteen years that haircut widens to a five-figure ending shortfall versus the fully-invested counterfactual. Yield context changes everything, which is why this quantifier separates the two sides: what the cash DOES earn (money-market rates currently pay real money) against what the same dollars hypothetically chase, exposing the true spread rather than the lazy 'cash earns nothing' cliché. The output deserves interpretation, not panic: buffers exist to prevent forced selling and to fund opportunities, services with real value this tool deliberately does not price. The actionable question it sharpens is calibration — whether the buffer's job genuinely needs fifteen cents of every dollar, or whether eight would insure the household just as well while returning the difference to the compounding engine.
Formula
Blended return = cash% × cash yield + (1 − cash%) × invested return | Gap = FV(fully invested) − FV(blended)
Tips
- Count only deliberate cash — settlement sweeps and idle dividends add silent drag.
- Move working cash to money-market funds; yield shrinks the drag mechanically.
- Size the buffer to its job (months of spending), not to fear.
- Rerun whenever rates shift — the spread between cash and markets is not constant.
- Never eliminate the emergency sleeve to kill drag; insurance is not inefficiency.
Frequently asked questions
- What is cash drag in a portfolio?
- It is the performance shortfall caused by holdings sitting in low-yield cash instead of invested assets. Fifteen percent of a portfolio earning 4% while the remainder assumes 7% drags the blended return to about 6.35% — sixty-five basis points surrendered annually, compounding into large gaps over decades.
- How much cash should I keep in my brokerage account?
- Enough for its assigned jobs — typically three to six months of essential spending ($10,500–$21,000 on $3,500 monthly essentials) plus known near-term expenses. Beyond that, idle dollars are usually fear inventory, each extra month costing the spread between cash yield and your assumed invested return.
- Does holding cash always lose money?
- Only versus the counterfactual. Cash yielding 4–5% earns genuinely positive nominal returns; drag measures the GAP to whatever equities hypothetically deliver. In falling markets, cash outperforms by holding value — the cost shows up statistically over full cycles, not every year.
- Where should idle cash earn yield while waiting?
- Money-market funds inside the brokerage, high-yield savings accounts, Treasury bills or CDs depending on access needs and deposit insurance preferences. Moving $20,000 from a 0.01% sweep to a 4% money-market fund recovers about $800 yearly — pure recovered drag for one transfer.
- Can cash drag ever be worth it?
- Deliberately, yes. Dry powder enabled buyers to purchase through 2008–09 and 2020 lows without selling anything, and spending reserves prevented retirement-damaging liquidations. The quantified gap is the PREMIUM on flexibility and sleep — the skill is paying that premium consciously, sized to actual need.