It's difficult to know the precise size of the global financial services sector. The World Bank only collects data from 142 countries – it estimates the rest – and hasn't compiled new statistics since 2010. Moreover, the definition and scope of industries that fall within the financial services sector is not consistent among data sources. The Organization for Economic Co-operation and Development (OECD) suggests that financial services typically make up 20-30% of total service market revenue and about 20% of the total gross domestic product in developed economies.
The most recent notable attempt at compiling earnings estimates for the global financial services sector was made by the McKinsey Global Institute in 2011. Its figures center around retail banking, life insurance, and property and casual insurance. According to the McKinsey Global Institute report on consumer financial services, these three service areas generate approximately $6.6 trillion in annual revenue and has tended to grow at a 6% compound annual rate over the preceding decade.
The McKinsey Global Institute also suggested that retail banking, life insurance, and property and causality insurance make up approximately 60% of total financial services sector sales. It can be extrapolated from that estimate that the total revenue of the global financial services sector in 2011 was roughly $11 trillion.
To figure out what percentage of the global economy that $11 trillion represents, a total estimate of global GDP is required. The International Monetary Fund (IMF) estimated that the total global economy was worth $77.6 trillion in 2014. If global financial services kept up its 6% growth rate for the years between 2012-2014, then its 2014 figure would be $13.1 trillion.
Using these 2014 figures and calculations, the financial services sector comprises about 16.9% of the global economy, as measured in GDP. Further data from the IMF shows that the total service economy makes up about 60-65% of total global revenue. If the OECD's suggestion that financial services are between 20% and 30% of the total service market, then financial services would comprise between 12% and 19.5% of the total global economy.,