Global Macro Hedge Fund Strategies

Two hedge fund managers, Amanda and Brian, operate distinct global macro funds that focus on analyzing macroeconomic trends to capitalize on global market movements. In Q1 of the current fiscal year, both managers identified critical shifts in monetary policies across several major economies.

Amanda initiated a long position in emerging market currencies, translating her bullish outlook on these economies' prospects post-easing of quantitative tightening in the developed world. She expected these currencies to appreciate due to capital inflows driven by positive sentiment and higher yielding investments.

Meanwhile, Brian took a contrarian approach, shorting U.S. Treasury bonds. His strategy was based on expected inflation rising due to increased government spending and consumption, which he believed would precipitate higher interest rates and subsequently lower bond prices.

Given the differing strategies and inherent risks associated with such positions in global macro trading, which of the following is most likely an underlying assumption that both managers must validate to ensure their strategies are viable?