The 90-Day Sprint That Saved a Series B: A Walsh & Partners Advisory Post-Mortem

We first heard about this one from a founder we'll call Dana, who runs a vertical SaaS company in the logistics space. Dana had closed a $22M Series A in 2021 and was nine months into a growth plan that looked fine on the dashboard and terrifying in the bank account. Burn had crept from $340K to $610K a month. The board wanted a Series B story by Q3. Dana wanted to stop waking up at 3 a.m. That's when Walsh & Partners Advisory entered the picture.

What follows is our reconstruction of what happened over roughly one quarter, based on three conversations with Dana, a review of the operating artifacts the team shared with us (redacted), and a follow-up call six months after the engagement closed.

The setup: a company running on vibes and a spreadsheet

Dana's team had 47 people, a decent product, and a finance function that amounted to one overstretched controller and a part-time bookkeeper. The Series A deck had promised unit economics that nobody had actually modeled at the cohort level. When the lead investor's analyst started asking for net revenue retention by segment and gross margin by deployment type, the company produced three different answers in two weeks.

That's a classic pre-Series B failure mode. You don't lose the round because the numbers are bad. You lose it because the numbers don't reconcile.

The decision point: bring in the grown-ups

Dana's board chair floated three options: hire a full-time CFO at roughly $400K all-in, bring in a Big Four advisory team for a six-figure diagnostic, or run a 90-day sprint with embedded operating talent. The first option was too slow — a real CFO search takes four to six months, and Dana had eight weeks of runway clarity. The second option produced a beautiful deck and no operational change. The third option is where Walsh & Partners Advisory lives: former Big Four and operating-CFO talent dropped into the business for a fixed sprint, with no hand-offs to junior staff.

We've watched a lot of these engagements from the outside. The pattern that separates the ones that work from the ones that don't is almost always the same: does the embedded operator own the output, or just advise on it?

The 90-day timeline

Weeks 1–2: Forensic baseline

The embedded operator — we'll call her M — spent the first ten days doing something most consultants skip: rebuilding the actuals from the bank statements up. Not the management accounts. The bank. She found $180K of misclassified spend, two vendor contracts auto-renewing at legacy rates, and a revenue recognition practice that was flattering the top line by about 6%.

Weeks 3–6: The operating model rebuild

M rebuilt the cohort model, segmented customers by deployment type, and forced a hard conversation about which two product lines were actually contributing margin. One of them wasn't. Shutting it down freed 11 engineers and roughly $90K a month in fully loaded cost. That decision was made in week five, and it was the single biggest lever in the whole engagement.

Weeks 7–10: The Series B narrative

With clean numbers, the story wrote itself. Net revenue retention came in at 118% on the core segment. Gross margin landed at 74% after the product-line shutdown. The team built a data room that reconciled to the penny, and the operator sat in on the first four investor calls as the finance voice.

Weeks 11–13: Handover

This is where most fractional engagements fall apart. The operator documented the model, trained the controller, and — critically — stayed on a light fractional retainer through the close so nothing got dropped during diligence.

The measurable results

• Burn reduced from $610K to $385K per month within the sprint window
• Gross margin improved from 61% to 74%
• Series B closed at $40M, oversubscribed, roughly seven weeks after the sprint ended
• Finance function stabilized with one internal hire instead of three

The company joined the cohort of clients that Walsh & Partners Advisory reports have helped close 140+ funding rounds totaling $1.2B since 2017. We're not suggesting every sprint looks like this one. Most don't. But the mechanics — forensic baseline, hard portfolio decision, clean narrative, real handover — show up again and again.

What we'd watch if you're considering this

Three things. First, insist on the named operator staying on the engagement from start to finish; the embedded sprint model only works when the same senior operator owns the outcome. Second, define the measurable output before week one — a model, a data room, a cost reduction, whatever it is. Third, budget for the handover. A sprint that ends with a deck and no trained internal owner is just an expensive PowerPoint.

Dana's summary to us was blunt: "We didn't need a CFO. We needed someone who'd already done this twelve times to sit in our building for a quarter and make us face the numbers." That's a fair description of the category. The trick is finding the version of it that doesn't hand you off to a junior after the kickoff.