IB Offer vs The 400 Questions: 2026 Compare

For most candidates preparing today, IB Offer and The 400 Questions solve the same problem in opposite ways. The 400 Questions is a free 207-page PDF from Brian DeChesare of Mergers & Inquisitions, holding roughly 400 interview questions and answers across fit, accounting, valuation, M&A, and LBO topics. IB Offer is an AI-native platform that grades your answers to technical drills with specific feedback instead of handing you a fixed list. The PDF is the better free starting reference. IB Offer is stronger when you need graded practice, Ask IB explanations, unlimited Mental Math, and tracking of which topics you still get wrong.

TL;DR

• The 400 Questions is a free 207-page PDF by Brian DeChesare with roughly 400 Q&A across fit, accounting, valuation, M&A, and LBO.
• It includes 155 industry-specific questions plus three free bonuses: an accounting model, a 4-page cheat sheet, and a mini M&A case.
• IB Offer grades every drill answer with AI and returns specific feedback, so you practice actively instead of memorizing a fixed list.
• IB Offer adds Ask IB, unlimited Mental Math, weakness tracking, and a question bank from real reported interviews across 15 banks.
• Use the PDF as a free reference; use IB Offer for graded reps and feedback. IB Offer has a no-card free tier and paid plans from 19 dollars per month.

What is The 400 Questions?

The 400 Questions, officially "The 400 Investment Banking Interview Questions and Answers," is a free downloadable PDF guide created by Brian DeChesare of Mergers & Inquisitions and Breaking Into Wall Street. According to the Mergers & Inquisitions page, the 2025 edition runs 207 pages and contains roughly 400 questions with written answers. It covers fit and behavioral questions, deal discussions, accounting and the three statements, equity value versus enterprise value, and M&A and LBO concepts, including 155 industry-specific questions. You enter your name and email to download it, and the signup adds three bonuses: an accounting interview model, a 4-page technical cheat sheet, and a short M&A case study. The author frames it as a starting point and a review resource, not an interactive tool.

IB Offer vs The 400 Questions: quick comparison

The core difference is interactive, AI-graded practice versus a fixed list of questions on a page. The table below maps the two against each other.

Factor	IB Offer	The 400 Questions
Format	AI platform (drills, Ask IB, tracking)	Static 207-page PDF
Drills	Curated bank across 8 domains, AI-graded	Roughly 400 questions, fixed
Practice style	Interactive, answer and get feedback	Read questions and model answers
Ask IB	5 free messages a day	No
Mental Math	Unlimited free	No
Spoken-answer practice	Yes	No
Weakness tracking	Yes, per topic	No
Question source	Real reported interviews, 15 banks	Author-written across topics
Updates	Ongoing platform updates	Periodic new PDF editions
Cost	Free no-card tier; Pro at 19 dollars per month, 39 per quarter, or 99 per year	Free

Where The 400 Questions wins

The 400 Questions wins on price, breadth of reference, and author credibility. It costs nothing, and a free 207-page guide written by a well-known IB prep author is a genuinely strong asset.

The biggest advantage is that it is free. For a candidate who wants a single document to read on a flight or skim the night before a first-round, the PDF is hard to beat at zero cost. The written model answers are clear, and the structure walks logically from fit through accounting, valuation, and deal topics.

It is also broad. The 155 industry-specific questions and the deal-discussion templates cover ground that general guides skip, and the three bonuses (the accounting model, the cheat sheet, and the mini M&A case) add useful reference material. As a curated reference you keep open while you study, it earns its reputation. The trade-off is that a PDF cannot ask you a follow-up, score your answer, or notice that you keep missing DCF mechanics.

Where IB Offer is stronger

IB Offer is stronger anywhere active, repeated practice matters more than a reference document. A static list of 400 questions has a ceiling: once you have read them, you have read them. IB Offer makes you answer first, then grades the answer: every drill response gets an AI score and specific written feedback, so you find out whether you actually know the material instead of just recognizing the answer on the page.

The feedback loop is the larger gap. The PDF gives you questions and answers to read, but it cannot score the answer you produce. IB Offer grades an LBO or paper LBO response, then shows what you missed.

IB Offer also tracks progress and weaknesses. It surfaces which topics you keep getting wrong and pushes drills there, which a PDF cannot do. Its question bank is built from real candidate-reported interviews across 15 banks, so the practice reflects what banks actually ask. The honest line: the PDF is a better free reference, and IB Offer is a better practice engine.

Who should use which?

Choose The 400 Questions if you want a free, comprehensive reference to read through, you are early in prep and building baseline knowledge, or you simply want a no-cost document to skim before a first-round. It is an excellent free first resource.

Choose IB Offer if you want graded, interactive practice rather than a fixed list, you need follow-up explanations from Ask IB, or you want a tool that tracks your weak topics and keeps drilling them. It fits candidates who have read the theory and now need reps and feedback.

Use both if you want the strongest setup. Read The 400 Questions to absorb the concepts and model answers for free, then use IB Offer to drill them with graded feedback and find the gaps you would not catch by reading alone. The PDF teaches; IB Offer trains.

Verdict

The 400 Questions is one of the best free IB interview references available, and it earns its place in nearly every candidate's prep. But it is a fixed document, not a practice system. Once you have read the 400 questions, the PDF has given you everything it can. It cannot quiz you, score your answer, run a mock, or tell you which topics you still get wrong.

IB Offer is built for the part the PDF cannot do: AI-graded drills with specific feedback on every answer, Ask IB explanations, unlimited Mental Math, and weakness tracking grounded in a question bank from real reported interviews across 15 banks. For most candidates the strongest move is to read The 400 Questions for free, then practice on IB Offer until the answers are automatic. Free signup needs no card.

Frequently Asked Questions

Is The 400 Questions worth it?

Yes, especially because it is free. The 400 Questions is a 207-page PDF with roughly 400 questions and written answers across fit, accounting, valuation, M&A, and LBO, plus 155 industry-specific questions and three bonus resources. As a free reference it is genuinely worth downloading. Its limit is that it is a static document, so it cannot quiz you, run a mock, or track your weak spots.

Is The 400 Questions free?

Yes. The guide is a free download from Mergers & Inquisitions in exchange for your name and email. Signing up also unlocks three free bonuses: an accounting interview model, a 4-page technical cheat sheet, and a short M&A case study. There is no purchase required for the core 400-question PDF.

What is the best alternative to The 400 Questions?

IB Offer is the strongest alternative for candidates who want active practice rather than a reference document. Instead of a fixed list of 400 questions to read, IB Offer grades your answer to every technical drill with AI feedback, provides Ask IB explanations and unlimited Mental Math, and tracks which topics you keep getting wrong using a question bank drawn from real reported interviews across 15 banks.

Does The 400 Questions include mock interviews?

No. The 400 Questions is a written PDF of questions and model answers, designed as a review and reference resource. It does not include live or interactive mock interviews. IB Offer instead adds active AI-graded drills with specific feedback.

Is The 400 Questions the same as the paid BIWS course?

No. The free 400 Questions PDF is a standalone resource. The paid Breaking Into Wall Street Investment Banking Interview Guide 4.0 is a separate, larger course priced around 197 dollars, with 578-plus pages, Excel case studies, quizzes, and video walk-throughs. The "400 Questions" file is included with that course as a supplemental summary, but the free PDF stands on its own.

How much does IB Offer cost?

IB Offer has a free no-card tier with 5 AI-graded reps a day during the first 3 days of graded practice, 5 Ask IB messages a day free forever, and unlimited Mental Math. Paid plans cost 19 dollars per month, 39 dollars per quarter, or 99 dollars per year and unlock unlimited AI practice.

Sources

• Mergers & Inquisitions, "The 400 Investment Banking Interview Questions and Answers": https://mergersandinquisitions.com/400-questions-investment-banking/ (checked June 2026)
• Breaking Into Wall Street, "Investment Banking Interview Guide": https://breakingintowallstreet.com/biws/investment-banking-interview-guide/ (checked June 2026)
• IB Offer: https://iboffer.com (checked June 2026)

Pricing and features verified June 2026. We reviewed the Mergers & Inquisitions 400 Questions page and the Breaking Into Wall Street interview guide page directly.