McKinsey, Bain, and BCG are often referred to as "MBB" for short. "Big 4" refers to Deloitte, EY, KPMG, and PwC.
Read on to find out how these two groupings of firms compare. Let's dive in!
You can think of the difference between MBB and Big 4 like this:
MBB only provide consulting services. Consulting is their bread and butter and they've been doing it for a while – McKinsey since 1926, BCG since 1963, and Bain since 1973.
By comparison, most of the Big 4 firms started formally offering consulting services in the 1990s, then sold them off in the 2000s, and then restarted them in the 2010s.
So MBB has been in the consulting game for much longer.
The Big 4 firms provide three main kinds of services: tax, audit, and consulting.
- Tax generally means helping companies prepare tax returns and giving them advice on how to lower their tax burden.
- Audit means checking companies' financial statements so people like investors and banks trust the company is performing as it claims to.
- Consulting is about helping companies improve their performance or reach their goals.
Out of these three services, audit is the Big 4's bread and butter. It's what brings in the bacon even when the economy is bad. And it's what made the Big 4 "big" in the first place – they audit the majority of companies on the stock market. That's why you'll also hear people refer to the Big 4 as "audit firms."
Why did the Big 4 audit firms decide to provide consulting services? Primarily because it's hard to grow their business solely through their audit services.
Deloitte and the other Big Four firms ... have all increasingly emphasized and invested heavily in consulting in recent years. It’s easy to understand why: It’s lucrative, virtually unregulated, and offers greater potential for growth than the more-mature audit field. Advising companies on digital transformation and management is less structured and offers greater creative challenges than verifying their numbers.
– Quartz
The Big 4 firms now make more money from consulting than auditing.
When it comes to the types of consulting services the firms provide:
Out of all the different types of consulting, MBB are most well-known for their work in strategy consulting – the branch of management consulting that helps companies devise their overarching business strategy.
This reputation in the field isn't solely because they got to strategy consulting first. Another firm – Arthur D. Little – arguably beat them to it.
It's also not because strategy is the only thing they do. They've increasingly taken on projects where they implement strategies instead of coming up with them.
Throughout history, the firms came up with enduring tools and frameworks that have become the ABCs of business strategy. From BCG's "growth-share matrix" to McKinsey's "7-S Framework" and Bain's "Net Promoter Score," these aren't just tools; they're the lenses through which businesses worldwide now see their paths to growth and success.
(Here at Prosple, we use the Net Promoter Score to measure how our clients view us, for instance!)
So it's safe to call MBB "masters of strategy" because they've shaped the very way we think about and execute business strategy. And because of this reputation, they're the ones top global companies will turn to first for any type of strategy work.
On the other hand, the Big 4 are more like jacks of all trades when it comes to consulting. That's because they offer all kinds of consulting services from HR consulting to tech consulting to financial advisory consulting.
Now, the Big 4 firms also have strategy consulting arms. Unlike MBB which started in strategy though, the Big 4 gained strategy consulting expertise by acquiring smaller strategy firms.
During the 2000s, the Big 4 also expanded their consulting businesses through further acquisitions. Most notably, Deloitte acquired Monitor Group, PwC acquired Booz & Company, and Ernst & Young acquired Parthenon. As the firms have begun to count more on consulting resume, they acquired branded strategy houses to move into the most lucrative sector of consulting.
It should be noted that the Big 4 firms's strategy arms operate semi-independently of the rest of the firm.
Worth noting that some Big-4’s acquired boutique strategy shops (Parthenon by EY, Booz by PwC, Monitor by Deloitte etc.) just so they could inorganically break into this space but those acquired firms still operate distinctly from the larger Big-4 parent group to avoid dilution of prestige/reputation.
In the industry, MBB are known to be the most prestigious and among the highest-paying firms. The Big 4 are less prestigious but still decently paid.
To be more precise, here's the general consensus on how firms rank in the whole field of management consulting:
Their prestige is reflected in who they hire. MBB hire from top colleges and business schools in the country. On campuses like Yale, for instance, you'll encounter a lot of students applying for MBB and to a lesser extent Deloitte. However, it's unlikely you'll hear about anyone applying for KPMG, EY, or PwC.
The prestige doesn't just mean you have a fancier name on your resume. It also affects how much the firms can charge for their services – and how well they can treat their employees!
A typical strategy case costs between $500,000 and $1,250,000. This variance is driven by the premium the firm is able to command (e.g., McKinsey will usually charge more than say, LEK, because of the premium their brand commands), the length of the case and the number of consultants required to do the work.
– Former consultant @ BCG
The big three [MBB] ... charge the highest fees. One of the early influencers in shaping McKinsey and Company, Marvin Bower, talked a lot about charging the high fees as a way to symbol that they were going to signal that they were going to do the best work.
Charging the highest fees gives the companies the ability to do a number of things. It enables consultants to only have to work on one project at a time. At some other boutique firms and other firms in the Big 4 space, a lot of times consultants are working on more than one project at a time. This ... makes it more challenging to go as deep as these firms can in terms of a structured problem-solving approach.
Additionally, they're also growing quite fast. I know BCG has been growing in a crazy clip for the past 10 to 15 years and is always reinvesting more in people and training globally.
Finally, they have the most resources dedicated to training. They make conscious choices about sending people to training for two weeks. They take them out of the office and say "This is all you need to worry about for two weeks" and go super deep on what those problem-solving processes are for.
At McKinsey, I went through several full-week trainings which were really intense and often times harder than some of the work I was doing during the working week, but in each of those experiences you're getting hands-on coaching from other consultants and ... in the weeks following the training you get the sense that you were able to level up your skills.
– Former consultant @ McKinsey and BCG
MBB are at the top of the consulting world, so it follows that the Big 4 – and practically any other firm – are less prestigious. This means the Big 4 tend to charge less for projects and also pay their consultants less.
Big 4 firms typically tend to operate at the lower levels of the value chain. Typically, these firms are highly geared towards Financial Services Institutions ... As such, Tier-1 and highly strategic projects are the mainstay of MBB and the Big-4 typically do not have the credentials to operate in that space.
MBB has a more elite reputation and is considered more prestigious, which means they are also more selective in terms of who they hire.
Big 4 projects tend to be seen as high volume, with the implication that high volume = low quality. MBB can certainly bill their clients for more, and as Big 4 we are often reminded to only perform the work that we are paid for. ("Don’t provide a Cadillac for the price of a Corolla!")
A lot of Big 4 negotiations with the clients on the statement of work are a tug of war between what activities to include vs how much the client wants to pay. So I don’t necessarily think it’s low quality, but just very limited scope by the time negotiations are done.
A $2M proposal where we start off with all sorts of activities and solutions for the client to fix their problem the right way can be paired down for $500K where the client just wants the most basic package and the best bang for their buck.
– Consulting manager @ EY
It's worth noting that the strategy practices of the Big 4 (i.e. EY Parthenon, PwC's Strategy&, Deloitte Monitor) are also more prestigious and better-paid than their other consulting practices.
For specifics on entry-level pay at different consulting firms, see What's management consulting? A guide for students.
Both MBB and the Big 4 have big-name clients (think: Fortune 500 companies). The same company might hire Deloitte or PwC for tech consulting work and then hire Bain or BCG for strategy consulting work.
It's probably more meaningful to compare how MBB and the strategy arms of the Big 4 compare. In the strategy space, it's safe to say that:
The reasons why people should come to EYP are still the same as always — there are many top-notch practices (education, tech diligence, sell and separate/divestitures), the partners are broadly easier to work with than at other firms (they don’t have to sell as much given that broader EY brings us so much work), and we continue to sell interesting projects in all sectors.
The reasons not to come are also the same as they’ve always been — comp lags a little ... , we win our most interesting strategy projects on price, and most people do one of two types of work (PE diligence or divestitures).
– Consultant @ EY Parthenon
You can get an idea of what due diligence work means from this Strategy& (PwC) consultant.
[EMBED] https://www.youtube.com/watch?v=lRfTNiRnkyA
Also, keep in mind large, blue-chip companies aren't the only ones who hire consultants. Governments, start-ups, and non-profit organizations do too. At MBB, you're more likely to be able to work on pro bono (volunteer) projects for, say, a local board of education.
In terms of the nature of the work, at the junior-level, you'll be crunching a lot of data and doing "grunt" work at any consulting firm you work for.
The difference is that in the Big 4, you'd spend a greater proportion of your time making PowerPoint presentations.
I started to think that ... this didn't really align with my long-term goals, that I wasn't really gaining any transferable skills because a majority of my time at KPMG was spent literally doing PowerPoints graphic design more so than anything else.
– Former consultant @ KPMG
You'd also make presentation decks at MBB, but less so. The firms are known to outsource their PowerPoint presentation-making to staff in other countries, so their consultants can focus on coming up with insights.
D[eloitte] focused way more on polish - things like proper grammar and and sexy slides. At McK[insey], spelling errors and imperfect formatting was fine, but the bar for number/quality of insights was MUCH higher.
– Former intern @ Deloitte / consultant @ McKinsey
At the Big 4, you'll also need to be more worried about your "utilization rate" – this is how much time you spend on projects – i.e. the amount of time the firm can charge clients for.
Staffing was a hot mess at D[eloitte], with projects staffed almost exclusively through networks and lots of random sucking up to partners with the hopes of being staffed on something cool - since utilization also counts at D[eloitte], this also meant you could rarely wait for the right project.
Staffing at McK[insey] was a nice mix of using your staffing [manager] (IF you had a good one, which certainly wasn't guaranteed, I got super lucky with mine!) and networks - I could easily stay on the beach for a week or two if I was working on getting on the right opp for me
– Former intern @ Deloitte / consultant @ McKinsey
At the Big 4, if your utilization is lower than your peers, you'll need to explain yourself – which is why Big 4 consultants will take on more non-client work which can include business proposals, recruitment work, among other things.
Basically, as a consultant, you charge [the firm] through a project code when you're on a project and that counts as "utilization." When you're not on a project, you charge through a general code, which doesn't count as utilization.
You want a minimum utilization rate of 80-85% per year. If I'm on the bench and don't have a project to charge to, it looks bad, but you can wiggle your way out by saying "I helped with this initiative." That's why I've helped out with four rounds of recruiting and even a round of onboarding.
D[eloitte] 'required' extracurriculars in the form of non-client work and somewhat graded your performance on them...at McK[insey], they were more of an option, but an option that was noted that you were contributing to the firm at review time.
– Former intern @ Deloitte / consultant @ McKinsey
MBB has top talent whereas Big 4 has a wider range of talent.
MBB has more partners with advanced degrees such as MBAs. Big 4 has a more diverse partner base.
MBB also has a more rigorous recruitment process and focuses on top universities. Big 4 has a more diverse recruitment process, and they recruit from a wider range of schools. (For example, some of EY’s target schools aren’t necessarily Ivy League. We recruit from University of Texas, U of Southern California, U of Michigan, etc.)
– Consulting manager @ EY
I interned at Deloitte during my MBA and went full-time to McK[insey] ... Top end of talent at both firms was similar (i.e., I'd put the NYC D[eloitte] office up against any MBB office) but long-tail distribution at D[eloitte] was way lower than the 'worst' consultants I encountered at McK[insey]
– Former intern @ Deloitte / consultant @ McKinsey
There doesn't seem to be a consensus on whether work-life balance is better at MBB or the Big 4.
Some say the hours at MBB are better than at the Big 4.
MBB firms are billed by project and Big Fours are billed by hour. This also results in the fact that MBB consultants tend to work less than Big Four consultants. At MBB you would not have an incentive to work for more hours than you have to fulfill the workload. Thus, there is no benefit to the firm for you to work for more hours. Whereas in the big four firms, working more hours and billing more hours is actually advantageous.
– Co-founder @ PrepLounge
Others say that the hours at the Big 4 are better than at MBB.
Hours way worse at McK[insey], and because of the focus on insights rather than polish, meant that more time was spent thinking rather than scrubbing, so it felt like more of an always-on atmosphere, which could be quite exhausting.
– Former intern @ Deloitte / consultant @ McKinsey
Big 4 consulting firms typically offer better work-life balance than MBBs, though this depends on the project. The firms primarily focus on implementation projects which usually are scoped to take longer than strategy projects and tend to be more straightforward. Big 4 teams tend to work more with middle managers rather than the C-Suite like the MBB consultants.
All of this influences the culture of Big 4 firms. For example, Big 4 consultants tend to stay employed at the firms longer than MBBs (in the U.S., an average of ~9 years compared to ~2-3 years in MBBs). One of the unique selling points for the Big 4 consulting firms is they have consistently been ranked as great places to work:
- EY has been ranked for the past 24 years on Fortune’s 100 Best Companies to Work For. In 2022, EY ranked #52 with 90% of the staff reporting they feel supported at work. As the COVID-19 pandemic changed how we work, EY implemented policies and programs that support the staff, such as 2 week-long vacation breaks in summer and winter in the U.S. and two days a week work from home policy in the UK.
- Deloitte, PwC, and KPMG were also ranked as Great Places to Work, ranking #24, #41, and #63, respectively, with a majority of employees citing the people and benefits.
What about the strategy arms of the Big 4? Work-life balance is likely similar to MBB since both groups of firms focus on strategy consulting. However, the Big 4 strategy firms likely have a slightly worse work-life balance as they work on more short-term due diligence projects.
It is notoriously known that due diligences which are shorter term projects around three weeks typically have pretty bad hours ... Again it's not terrible it's just longer and they expect you to be there present a lot of the time actively contributing.
– Former consultant @ KPMG / consultant @ McKinsey
While this article was about the Big 4 and MBB firms, we hope these insights help you decide what kind of company you'd like to work in general!
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