What Is Due Diligence?
Due diligence is the structured process of investigating a company before committing to buy it, invest in it, or lend to it. In M&A, it takes place after a buyer has expressed serious interest, typically following a signed letter of intent, and before the definitive purchase agreement is finalized.
The goal is to verify the seller's claims and uncover problems that could change the price or kill the deal, from overstated revenue to pending lawsuits or customer concentration. Findings from diligence routinely lead buyers to renegotiate price, demand indemnities, or walk away entirely.
What Due Diligence Covers
Financial diligence examines the quality of earnings, testing whether reported EBITDA reflects sustainable performance or is inflated by one-time items and aggressive accounting. Legal diligence reviews contracts, litigation, intellectual property, and regulatory compliance, while commercial diligence assesses the market, competition, and customer relationships.
Larger deals also include tax, operational, technology, and environmental workstreams, each often handled by specialist advisors. For example, a buyer might discover that $20 million of a target's $100 million EBITDA came from a contract expiring next year, justifying a meaningfully lower purchase price.
How the Process Runs
The seller assembles thousands of documents in a virtual data room, and bidders submit written question lists that the seller's team answers on a rolling basis. Management presentations, site visits, and expert calls supplement the documents, all typically compressed into a few intense weeks.
In a competitive auction, the sell-side bank controls the flow of information, giving deeper access to the most serious bidders in later rounds. Accounting firms are often hired to produce a quality of earnings report that both sides rely on in negotiating the final price.
Due Diligence in Banking Life
For junior bankers, diligence means managing data rooms, tracking question logs, coordinating advisors, and updating models as new information arrives. It is unglamorous but critical work, since a missed red flag can turn into an expensive post-closing dispute or a failed acquisition.
In interviews, due diligence usually appears in walk-me-through-a-deal questions, where candidates are expected to place it correctly in the M&A timeline between the LOI and signing.
