Investors are overlooking Zambia’s political risk and buying the nation’s assets as the price of copper, its biggest export, rises. The yield on Zambia’s $1-billion Eurobonds due April 2024 have fallen 135 basis points this year to 7.55% on Wednesday. The southern African nation’s currency has appreciated 12% against the dollar in 2017, making the kwacha the continent’s best performer after Mozambique’s metical. Copper prices are at their highest in more than two years. The metal used in plumbing and electrical wiring accounts for about 70% of Zambia’s export earnings.