Risk assets rise in times of optimism, because they are believed to provide better returns when economies are expanding. For example: The classic risk assets include stocks, and also industrial commodities like oil, copper and iron ore that are in higher demand during times of expansion.
Most major global stock indexes like the S&P 500, FTSE 100, DAX, CAC, and Nikkei trend in a similar manner.
Higher yielding currencies (AUD, NZD) tend to rise in times of expansion relative to currencies from nations with lower interest rates, due to demand from carry trade.