Aon plc is a British-American professional services and management consulting firm that offers a range of risk-mitigation products. Aon has approximately 50,000 employees across 120 countries.
The Big Four are the four largest professional services networks in the world: Deloitte, EY, KPMG, and PwC. They are the four largest global accounting networks as measured by revenue. The four are often grouped because they are comparable in size relative to the rest of the market, both in terms of revenue and workforce; they are considered equal in their ability to provide a wide scope of professional services to their clients; and, among those looking to start a career in professional services, particularly accounting, they are considered equally attractive networks to work in, because of the frequency with which these firms engage with Fortune 500 companies.
PricewaterhouseCoopers International Limited is a multinational professional services brand of firms, operating as partnerships under the PwC brand. It is the second-largest professional services network in the world and is considered one of the Big Four accounting firms, along with Deloitte, EY and KPMG.
Horizontal integration is the process of a company increasing production of goods or services at the same level of the value chain, in the same industry. A company may do this via internal expansion, acquisition or merger.
Publicis Sapient is a global digital transformation consulting company and the digital business transformation hub of Publicis Groupe with 20,000 people and over 50 offices worldwide. It was originally established as Sapient in Cambridge, Massachusetts in 1990. In 2015, Sapient became an independent subsidiary of French multinational advertising firm Publicis, following a deal worth US$3.7 billion. It remains headquartered in Boston, Massachusetts, and as of February 2015, the leadership is retained.
Towers Perrin was a professional services firm specializing in human resources and financial services consulting, which merged in January 2010 with Watson Wyatt to form Towers Watson. The firm was a provider of reinsurance intermediary services and was active in the actuarial consulting arena with its Tillinghast insurance consulting practice.
The human resource consulting industry has emerged from management consulting and addresses human resource management tasks and decisions.
Watson Wyatt Worldwide, Inc. was a global consulting firm that merged in January 2010 with Towers Perrin to form Towers Watson. The firm's services included managing the cost and effectiveness of employee benefit programs; developing attraction, retention and reward strategies; advising pension plan sponsors and other institutions on optimal investment strategies; providing strategic and financial advice to insurance and financial service companies; and delivering related technology, outsourcing and data services. Its principal operating subsidiary, Watson Wyatt & Company, was a human capital consulting firm with operations in the Americas, Europe and Asia Pacific. Its corporate offices were in Arlington, Virginia.
Mercer is an American consulting firm founded in 1945. It is one of the four operating subsidiaries of global professional services firm Marsh McLennan. Mercer is headquartered in New York City with offices in 43 countries and operations in 130 countries. The company primarily provides human resources and financial services consulting services to its clients.
Jardine Lloyd Thompson Group plc, also known as JLT Group or simply JLT, was a British multinational corporation that had its headquarters in London, England. It provided insurance, reinsurance, employment benefits advice and brokerage services. It was a constituent of the FTSE 250 Index until it was acquired by Marsh McLennan in April 2019.
RBC Brewin Dolphin is one of the largest British wealth management firms with over 30 offices throughout the UK, Jersey and Ireland, and c. 2,000 employees. It provides investment management and financial planning services to individuals, companies, intermediaries and charities.
Willis Group Holdings plc was a multinational risk advisor, insurance brokerage and reinsurance brokerage company with its headquarters in the Willis Building in London until its merger of equals with financial services company Towers Watson in 2016. It was the world's third-largest insurance broker when measured by revenues.
Colliers International Group Inc. is a Canada-based diversified professional services and investment management company with approximately 18,000 employees in more than 400 offices in 65 countries.
MWH Global Inc. was a global water and natural resources firm providing technical engineering, construction services and consulting services. In 2016, MWH was acquired by Stantec Consulting Inc. The firm provided planning, design and construction management for water and natural resources projects around the world. The firm was headquartered in Broomfield, a suburb of the Denver metropolitan area in the state of Colorado of the United States, with operations in 35 countries. As of May 2015, MWH Global had a global staff of approximately 7,000 employees including builders, engineers, architects, geologists, operators, project managers, business consultants, scientists, technologists, and regulatory experts. MWH was listed as the 15th-largest employee-owned company in the United States.
EMB Consultancy, also known as EMB Actuaries and Consultants, is an international actuarial business consultancy and software provider. EMB was originally established as a strategic and actuarial advisor to non-life insurers. The company has developed and now operates in a growing range of business functions and sectors, such as banking, investments, asset management, fraud prevention, risk enterprise management, mergers and acquisitions and marketing. These are areas where the widespread collection and use of data and financial models have become commonplace.
Aon Hewitt was a provider of human capital and management consulting services headquartered in Lincolnshire, Illinois in the United States. From 500 offices in 120 countries, it provided consulting, outsourcing, and reinsurance brokerage services. The "Aon Hewitt" brand and legal entities have now been absorbed into the "Aon" business, leaving obsolete the names "Hewitt" and "Aon Hewitt."
Willis Towers Watson plc, branded as WTW and stylised in its logo as wtw, is a British-American multinational company providing insurance services. The company was founded in 2016, following a merger of the Willis Group and Towers Watson.
LifeWorks, formerly known as Morneau Shepell, was a human resources services and technology company headquartered in Toronto, Ontario, Canada. Established in 1966, LifeWorks served approximately 24,000 clients in North America. Besides North American offices, LifeWorks also had offices outside North America, including Brazil, Australia and the United Kingdom. LifeWorks was a publicly traded company on the Toronto Stock Exchange, with market capitalization of $2 billion.
BDO is an international network of public accounting, tax, consulting and business advisory firms that provide professional services under the name BDO. It is the fifth-largest accounting network in the world. Global fee income of the member firms in the network for the year ended 30 September 2021, including the members of their exclusive alliances, totaled US$12.8 billion. Each BDO member firm is an independent legal entity in its own country. The network, founded in 1963 as Binder Seidman International Group by firms from Canada, Germany, the Netherlands, the UK and the US, is coordinated by BDO Global Coordination B.V., with an office in Zaventem, Belgium. In 1973, the organisation adopted the name BDO, made up from the initials of the three founding firms: Binder (UK), Dijker (Netherlands) and Otte (Germany).
US$ 3.60 billion (2013) [2] 
