Greater freedom for funds to cross borders reshapes how domestic interest rates relate to global returns. When capital mobility is high, investors move quickly to exploit yield differences, and arbitrage pressures drive rates toward alignment across countries. Maurice Obstfeld of University of California, Berkeley explains that open financial markets strengthen the forces behind interest rate parity, while Kenneth Rogoff of Harvard University documents how financial globalization has historically narrowed long-run yield differentials between integrated economies. This is not automatic or complete; frictions change the outcome.
Mechanisms and constraints
Two related concepts explain convergence dynamics. Covered interest parity links rates via forward exchange markets and typically holds when arbitrage is straightforward. Uncovered interest parity depends on expectations about future exchange rates and is more fragile because it incorporates currency risk and risk premia. Claudio Borio of Bank for International Settlements highlights that transaction costs, regulatory differences, and counterparty risk frequently generate persistent spreads. Capital controls, asymmetric information, market depth and the supply of safe assets all act as constraints. In times of stress, perceived credit or liquidity risk can temporarily reverse convergence despite open capital accounts.
Relevance and consequences
Convergence lowers borrowing costs for countries and firms able to tap global markets, facilitating investment and consumption. It also transmits monetary conditions across borders, creating spillovers that can complicate independent policy making. Carmen Reinhart of Harvard University and other researchers have documented episodes where rapid capital flows and sharp shifts in global yields intensified financial instability and capital flight in vulnerable economies. On the human and territorial level, rate convergence can benefit urban and export-oriented regions while leaving peripheral or informal sectors exposed when sudden reversals occur. Environmental and infrastructure projects may gain cheaper financing under convergence, but project viability becomes more sensitive to global rate swings.
Policy responses shape the balance between benefits and risks. Macroprudential measures, targeted capital management and central bank coordination can mitigate volatility and preserve the convergence needed for efficient global capital allocation. Ultimately, capital mobility promotes cross-border interest rate convergence in principle, but the degree and stability of convergence depend on risk perceptions, institutional frameworks and policy choices that vary across countries and communities.