Optimizing WACC When the Bank of Canada Won't Sit Still

Weighted average cost of capital gets calculated once, used in a model, and then left alone far more often than it should be. That habit is forgivable in a stable rate environment. It's a genuine problem after the stretch Canadian businesses just lived through, where the Bank of Canada's policy rate round-tripped from near zero territory up to 5.00% and back down to 2.25% inside about four years, dragging every rate-sensitive line in a WACC calculation along with it.

The Round Trip, 2022 To 2026

The sequence is worth stating plainly because of how compressed it was. The Bank of Canada raised its overnight rate ten times across 2022 and 2023, bringing it to a peak of 5.00% (The Globe and Mail, 2026). Starting in the summer of 2024, the Bank reversed course, cutting nine times over the following year and a half to bring the policy rate down to 2.25% by late October 2025 (The Globe and Mail, 2026). Through the first half of 2026, the Bank held that rate steady across multiple consecutive scheduled announcements, describing 2.25% as sitting at the lower end of what it considers a neutral range, a level that neither stimulates nor restrains the broader economy (The Globe and Mail, 2026).

That's a 2.75 percentage point round trip on the base rate that underpins bank prime, which itself sat around 4.45% through the middle of 2026 (True North Mortgage, 2026). Any variable-rate term debt, any line of credit priced off prime, and any new financing quoted against current government bond yields all felt this directly. A WACC built in early 2023, when the policy rate was still climbing toward its peak, is describing a genuinely different cost structure than one built today.

Why Cost Of Debt Moved Faster Than Cost Of Equity

Cost of debt is mechanical. It's whatever the company is actually paying or would currently pay on new borrowing, and that number moves with the policy rate on a fairly short lag, especially for anything priced off prime rather than locked into a long-term fixed rate. Cost of equity is a different animal entirely. Built through a model like CAPM, it combines a risk-free rate, a beta, and an equity risk premium, the extra return investors demand for holding stocks instead of a safe government bond. The risk-free rate component moves with the interest rate cycle. The equity risk premium is stickier, shaped more by broader investor sentiment, volatility expectations, and macro uncertainty than by any single central bank decision.

That distinction matters more than it sounds. A period like 2024 to 2026, marked by trade tensions and tariff uncertainty between Canada and the United States alongside falling policy rates, is exactly the kind of environment where the risk-free rate falls while the equity risk premium can hold steady or even widen, since investors are pricing in more macro uncertainty even as short-term borrowing gets cheaper. The Bank of Canada's own 2026 commentary pointed to weak but resilient growth, GDP forecast at roughly 1.2% for 2026, alongside ongoing trade policy unpredictability as the dominant forces still shaping the outlook (The Globe and Mail, 2026). A WACC recalculation that drops the risk-free rate but leaves the equity risk premium assumption untouched from three years ago is only doing half the job, and probably understating the true cost of equity capital as a result.

The Part Most Recalculations Skip

Capital structure weights themselves shift with a rate cycle too, and this is the piece most WACC updates skip entirely. As borrowing got cheaper through 2024 and 2025, many private companies took on more debt relative to equity simply because it made sense to. That changes the actual weighting between debt and equity in the WACC formula, independent of what happened to either rate individually. A company that refinanced expensive 2023-vintage debt into cheaper 2025 or 2026 terms, and used some of the freed-up cash flow to fund growth with additional borrowing rather than new equity, has a meaningfully different capital structure today than the one embedded in an old WACC calculation, on top of the rate changes themselves.

A Practical Recalculation Cadence

There's no need to rebuild WACC every month, but an annual refresh is close to the minimum in an environment like the one Canada just went through. A more disciplined approach ties the recalculation to specific triggers: any Bank of Canada cumulative rate move exceeding roughly 50 basis points since the last calculation, any refinancing or new debt issuance that changes the actual cost of debt, and any capital raise or buyback that shifts the debt-to-equity weighting materially. Tying WACC updates to events rather than a fixed calendar catches the moments that actually matter without turning it into a constant, low-value chore.

What This Means For Decisions Made In 2023-2024

Any capital budgeting decision, expansion, acquisition, or major capital expenditure, that was evaluated using a WACC built at or near the 2023 rate peak was discounted against a materially higher hurdle rate than what the same project would clear today. Projects that were rejected as NPV-negative under a 2023-era discount rate are worth revisiting under current assumptions before assuming the original conclusion still holds. The reverse is also true: projects greenlit using an outdated, lower pre-hike WACC from 2021 or early 2022 may have cleared a hurdle that was already stale by the time capital actually deployed.

A Checklist

1. Recalculate cost of debt against your actual current borrowing terms, not the policy rate alone, since credit spreads move independently of the base rate.
2. Revisit the equity risk premium assumption specifically, rather than assuming it moved in lockstep with the risk-free rate.
3. Update capital structure weights to reflect your actual current debt-to-equity mix, especially if you refinanced or took on new debt during the cutting cycle.
4. Re-run any capital budgeting decision rejected under a 2023-vintage discount rate, since the hurdle it needed to clear was likely higher than today's.
5. Set an event-based trigger for future recalculations, such as a cumulative 50 basis point Bank of Canada move, rather than relying on memory to prompt a refresh.