In 1985 the international exchange rate intervention known as “The Plaza Accord” was carried out between the G-5 countries, the US, Japan, Germany, France, and the UK. In this study I employ the synthetic control method (SCM) to examine if there was a causal effect of The Plaza Accord on residential housing prices in Japan. Following the agreement Japan experienced a bubble in urban real estate and the stock market. I find small and insignificant effects of the Plaza Accord on real housing prices in the several years following it, providing evidence that the Accord did not exacerbate the bubble.

Portugal, Canada, and the United States were the countries with the highest house price to income ratio in 2024. In all three countries, the index exceeded 130 index points, while the average for all OECD countries stood at 116.2 index points. The index measures the development of housing affordability and is calculated by dividing nominal house price by nominal disposable income per head, with 2015 set as a base year when the index amounted to 100. An index value of 120, for example, would mean that house price growth has outpaced income growth by 20 percent since 2015. How have house prices worldwide changed since the COVID-19 pandemic? House prices started to rise gradually after the global financial crisis (2007–2008), but this trend accelerated with the pandemic. The countries with advanced economies, which usually have mature housing markets, experienced stronger growth than countries with emerging economies. Real house price growth (accounting for inflation) peaked in 2022 and has since lost some of the gain. Although, many countries experienced a decline in house prices, the global house price index shows that property prices in 2023 were still substantially higher than before COVID-19. Renting vs. buying In the past, house prices have grown faster than rents. However, the home affordability has been declining notably, with a direct impact on rental prices. As people struggle to buy a property of their own, they often turn to rental accommodation. This has resulted in a growing demand for rental apartments and soaring rental prices.

Estimated commercial land price bubble sizes of Japan’s prefectures (%).

Accessory Dwelling Unit (ADU) Market Outlook

According to our latest research, the Global Accessory Dwelling Unit (ADU) market size was valued at $8.4 billion in 2024 and is projected to reach $23.7 billion by 2033, expanding at a robust CAGR of 12.1% during the forecast period of 2024–2033. The remarkable growth in the Accessory Dwelling Unit market is primarily driven by the increasing demand for affordable and flexible housing solutions in urban and suburban areas, coupled with favorable zoning reforms and government incentives. As cities worldwide grapple with housing shortages and escalating property prices, ADUs have emerged as a viable solution, offering homeowners the opportunity to maximize their property’s utility, generate rental income, or accommodate multigenerational living. The proliferation of ADU-friendly policies, advancements in modular and prefabricated construction technologies, and shifting consumer lifestyles are collectively propelling the global ADU market into a new era of sustained growth and innovation.

Regional Outlook

North America currently dominates the Accessory Dwelling Unit market, accounting for the largest share of global revenues in 2024. This region’s leadership is underpinned by mature real estate markets, progressive urban planning policies, and widespread adoption of ADUs in states like California, Oregon, and Washington. The United States, in particular, has witnessed a surge in ADU permits and construction, driven by legislative reforms that encourage backyard homes and infill development to address acute housing shortages. Additionally, the presence of established ADU manufacturers, robust financing options, and growing homeowner awareness have contributed to North America’s commanding position, with the region projected to maintain a significant share throughout the forecast period.

The Asia Pacific region is poised to be the fastest-growing market for Accessory Dwelling Units, with an expected CAGR exceeding 14.5% through 2033. This rapid expansion is fueled by urbanization, rising middle-class populations, and innovative housing policies in countries such as Japan, Australia, and South Korea. In these markets, land scarcity, high property prices, and government support for compact living solutions are accelerating ADU adoption. The increasing prevalence of modular and prefabricated construction methods, combined with investment in smart home technologies, is enabling faster, more cost-effective deployment of ADUs, making Asia Pacific a hotspot for future market growth and innovation.

Emerging economies in Latin America and the Middle East & Africa are gradually embracing the ADU concept, albeit at a slower pace due to regulatory complexity, limited consumer awareness, and financing constraints. However, localized demand for affordable housing, population growth, and urban densification are beginning to drive interest in accessory dwelling units. Policy experimentation and pilot projects in cities like São Paulo and Cape Town are indicative of a broader shift towards flexible living solutions, though widespread adoption will depend on regulatory harmonization, public-private partnerships, and tailored financing models that address the unique challenges of these regions.

Report Scope

With the collapse of the U.S. housing market and the subsequent financial crisis on Wall Street in 2007 and 2008, economies across the globe began to enter into deep recessions. What had started out as a crisis centered on the United States quickly became global in nature, as it became apparent that not only had the economies of other advanced countries (grouped together as the G7) become intimately tied to the U.S. financial system, but that many of them had experienced housing and asset price bubbles similar to that in the U.S.. The United Kingdom had experienced a huge inflation of housing prices since the 1990s, while Eurozone members (such as Germany, France and Italy) had financial sectors which had become involved in reckless lending to economies on the periphery of the EU, such as Greece, Ireland and Portugal. Other countries, such as Japan, were hit heavily due their export-led growth models which suffered from the decline in international trade. Unemployment during the Great Recession As business and consumer confidence crashed, credit markets froze, and international trade contracted, the unemployment rate in the most advanced economies shot up. While four to five percent is generally considered to be a healthy unemployment rate, nearing full employment in the economy (when any remaining unemployment is not related to a lack of consumer demand), many of these countries experienced rates at least double that, with unemployment in the United States peaking at almost 10 percent in 2010. In large countries, unemployment rates of this level meant millions or tens of millions of people being out of work, which led to political pressures to stimulate economies and create jobs. By 2012, many of these countries were seeing declining unemployment rates, however, in France and Italy rates of joblessness continued to increase as the Euro crisis took hold. These countries suffered from having a monetary policy which was too tight for their economies (due to the ECB controlling interest rates) and fiscal policy which was constrained by EU debt rules. Left with the option of deregulating their labor markets and pursuing austerity policies, their unemployment rates remained over 10 percent well into the 2010s. Differences in labor markets The differences in unemployment rates at the peak of the crisis (2009-2010) reflect not only the differences in how economies were affected by the downturn, but also the differing labor market institutions and programs in the various countries. Countries with more 'liberalized' labor markets, such as the United States and United Kingdom experienced sharp jumps in their unemployment rate due to the ease at which employers can lay off workers in these countries. When the crisis subsided in these countries, however, their unemployment rates quickly began to drop below those of the other countries, due to their more dynamic labor markets which make it easier to hire workers when the economy is doing well. On the other hand, countries with more 'coordinated' labor market institutions, such as Germany and Japan, experiences lower rates of unemployment during the crisis, as programs such as short-time work, job sharing, and wage restraint agreements were used to keep workers in their jobs. While these countries are less likely to experience spikes in unemployment during crises, the highly regulated nature of their labor markets mean that they are slower to add jobs during periods of economic prosperity.

Estimation results in Japan (1980–1999).

Ratios of the average apartment price to the average monthly salary per capita in Tokyo and Osaka in Japan*.

From the onset of the Global Financial Crisis in the Summer of 2007, the world economy experienced an almost unprecedented period of turmoil in which millions of people were made unemployed, businesses declared bankruptcy en masse, and structurally critical financial institutions failed. The crisis was triggered by the collapse of the U.S. housing market and subsequent losses by investment banks such as Bear Stearns, Lehman Brothers, and Merrill Lynch. These institutions, which had become over-leveraged with complex financial securities known as derivatives, were tied to each other through a web of financial contracts, meaning that the collapse of one investment bank could trigger the collapse of several others. As Lehman Brothers failed on September 15. 2008, becoming the largest bankruptcy in U.S. history, shockwaves were felt throughout the global financial system. The sudden stop of flows of credit worldwide caused a financial panic and sent most of the world's largest economies into a deep recession, later known as the Great Recession. The World Economy in recession
More than any other period in history, the world economy had become highly interconnected and interdependent over the period from the 1970s to 2007. As governments liberalized financial flows, banks and other financial institutions could take money in one country and invest it in another part of the globe. Financial institutions and other non-financial companies became multinational, meaning that they had subsidiaries and partners in many regions. All this meant that when Wall Street, the center of global finance in New York City, was shaken by bankruptcies and credit freezes in late 2007, other advanced economies did not need to wait long to feel the tremors. All of the G7 countries, the seven most economically advanced western-aligned countries, entered recession in 2008, before experiencing an even deeper trough in 2009. While all returned to growth by 2010, this was less stable in the countries of the Eurozone (Germany, France, Italy) over the following years due to the Eurozone crisis, as well as in Japan, which has had issues with low growth since the mid-1990s.

From the Summer of 2007 until the end of 2009 (at least), the world was gripped by a series of economic crises commonly known as the Global Financial Crisis (2007-2008) and the Great Recession (2008-2009). The financial crisis was triggered by the collapse of the U.S. housing market, which caused panic on Wall Street, the center of global finance in New York. Due to the outsized nature of the U.S. economy compared to other countries and particularly the centrality of U.S. finance for the world economy, the crisis spread quickly to other countries, affecting most regions across the globe. By 2009, global GDP growth was in negative territory, with international credit markets frozen, international trade contracting, and tens of millions of workers being made unemployed.

Global similarities, global differences

Since the 1980s, the world economy had entered a period of integration and globalization. This process particularly accelerated after the collapse of the Soviet Union ended the Cold War (1947-1991). This was the period of the 'Washington Consensus', whereby the U.S. and international institutions such as the World Bank and IMF promoted policies of economic liberalization across the globe. This increasing interdependence and openness to the global economy meant that when the crisis hit in 2007, many countries experienced the same issues. This is particularly evident in the synchronization of the recessions in the most advanced economies of the G7. Nevertheless, the aggregate global GDP number masks the important regional differences which occurred during the recession. While the more advanced economies of North America, Western Europe, and Japan were all hit hard, along with countries who are reliant on them for trade or finance, large emerging economies such as India and China bucked this trend. In particular, China's huge fiscal stimulus in 2008-2009 likely did much to prevent the global economy from sliding further into a depression. In 2009, while the United States' GDP sank to -2.6 percent, China's GDP, as reported by national authorities, was almost 10 percent.