EY's head, Janet Truncale, took over as CEO and global chair last July, promising to foster greater collaboration across the Big Four firm's international network.Nine months into the role, EY is starting to see some big changes to its business lines and global structure.An EY spokesperson confirmed to BI that the firm plans to merge its 18 existing geographical regions into 10 superregions. Financial News first reported the plans.In another change, EY announced in a press release this week that it is expanding its EY-Parthenon brand to represent the entire EY strategy and transactions service line.EY-Parthenon, the firm's strategy consulting division, was previously part of the S&T service line and had around 9,000 workers at the start of this year. The newly expanded division now comprises 25,000 employees across 150 countries.The move is designed to strengthen the full consulting transformation capabilities of the organization, EY said.Andrea Guerzoni, EY-Parthenon's Global Vice Chair, added that client demand for strategic consulting had evolved amid geopolitical uncertainty and tech-driven transformational change. The expansion would help meet that changing demand, he said.Last year, the firm's sector strategy also received a shake-up when EY streamlined its core industries from eight to six.EY's key sectors are now:During the process, health, science, and wellness were merged with the consumer industry, as were energy and resources, advanced manufacturing, and mobility.The Big Four firm has laid off some workers as it implements the changes.Last week, EY confirmed to Business Insider that it was restructuring its UK Law business by "focussing on strategic areas with greater alignment to the broader EY business." The firm said it would continue to strengthen capabilities in corporate law, company secretarial, tax litigation, and immigration but would be laying off workers across other areas of its UK Law division.Partner numbers in the UK, where the global consulting and accountancy firm is headquartered, declined by 43 in 2024, according to publicly available data reviewed by BI.The previous year, the firm had added 27 partners to its ranks.The waves of change at EY come in the wake of the firm's failed bid to split its consulting and audit lines under the previous CEO, Carmine Di Sibio. Codenamed "Project Everest," the bid collapsed in April 2023 amid infighting and opposition from senior US partners.Truncale took over as EY's global chair and CEO in July 2024.In her first public statement as global CEO, she launched a new strategy called "All in," which emphasized collaboration and EY's unity as a single global operation — a clear break from the "Project Everest" mission."The All in strategy is about shaping EY's next $50b through purposeful growth," Truncale said. The goal was to "build an even stronger organization by creating new ways to collaborate across EY's vast geographical footprint."Truncale is also tasked with helping EY recover from a dramatic slowdown in growth last year, a trend that also hit PwC and Deloitte amid an industry-wide drop in demand.In the 2024 financial year, EY's annual revenue growth fell to 3% from 16% the previous year, its poorest performance since 2010. Partner payouts in the UK were down by 5% last year.Have a tip? Contact this reporter via email at pthompson@businessinsider.com or Signal at Polly_Thompson.89. Use a personal email address and a nonwork device; here's our guide to sharing information securely.