Sebastian Janus

Case Study: Leading a Finance Department While Acquisitions Run

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A B2B SaaS company with more than 100 employees, a growth investor's portfolio company. Four months as interim CFO leading a five-person finance team, building PE-grade reporting and supporting the M&A activity on the finance side.

Cover image: leading a finance department while acquisitions run – four-month interim CFO mandate

An anonymised case description from an actual interim CFO mandate. Sector, scale and type of shareholder are stated; the company name is not. All details come from the mandate description on the interim CFO references page. Results are not broken down by date there, so they are given here for the mandate as a whole.

Starting position

A B2B software company on a subscription model with more than 100 employees, owned by a growth investor. The finance department consisted of five people. The shareholder was pursuing a buy-and-build strategy, so M&A activity ran alongside the day-to-day business.

An existing team of five is a different starting position from an unfilled finance function: the work consists less of taking on tasks personally than of ordering them – and of translating the shareholder's requirements into routines the team can keep running after the mandate ends.

Brief

Interim CFO with operational responsibility for the finance department and leadership of the five-person team, and at the same time a sounding board for management and the shareholder. Mandate type: CFO transition with post-merger integration.

Scope

  • Operational responsibility for a finance department of five
  • Sounding board for management and the shareholder
  • Finance-side support for the M&A activity under the buy-and-build strategy
  • PE-grade reporting, forecasting and KPI framework
  • Structuring the finance organisation, its processes and systems

Approach

The same order applied that has proven itself across these mandates: reporting capability and a cash forecast first, then planning, then systems. With an existing team a second layer comes in – responsibilities, approval routes and a closing calendar that holds once the interim appointment has ended.

The M&A activity ran in parallel. In practice that means the monthly close cannot stall while due diligence and integration absorb capacity. Separating the two strands – operations with the team, transaction with the interim CFO – is why the role is frequently filled externally in this phase.

Result

  • A finance department of five led operationally
  • PE-grade reporting, forecasting and KPI framework established
  • Finance organisation, processes and systems structured
  • M&A activity under the buy-and-build strategy supported on the finance side

Duration

Four months, June to September 2025.

Does this match your situation?

Where a finance team exists but the steering does not, the question is less who does the work than who sets the order. Background on this mandate type: interim CFO in private equity and consolidated accounts after buy-and-build. How an engagement runs is on the interim management page; all mandates at a glance on the interim CFO references page.

Sebastian Janus
Interim CFO for private-equity and venture-capital backed companies, founder of nugrow GmbH

Sebastian Janus is an interim CFO for private-equity and venture-capital backed companies, with more than 15 years in finance leadership, fundraising, M&A and restructuring. He founded one of the first German online shoe retailers in 2005, took it through two exits and then served as e-commerce CFO at a listed retail group. He has run nugrow GmbH in Bochum since 2018.

About the author

This article is by Sebastian Janus, interim CFO and finance operating partner. He founded one of the first German online shoe retailers in 2005, took it through two transactions and then served as e-commerce CFO at a listed retail group. Since 2018 he has run nugrow GmbH in Bochum, taking on finance responsibility on a temporary basis – mostly at private-equity and venture-capital backed SaaS and tech companies.

Sebastian Janus: profile and career

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