The episode involving hedge fund manager George Soros taking on the Bank of England in 1992, by betting against the sterling pound and "dramatically" destroying the United Kingdom's monetary system, is a stark example, he said.
"To put it simply, foreign exchange speculations have been and continue to be a threat to economies, especially small, open ones like ours," added Mr Heng.
Singapore, being a financial hub, had portfolio and banking-related flows that amounted to $294 billion last year, amid volatility in the global financial markets sparked by the pandemic, he noted.
This represented 63 per cent of gross domestic product.
"MAS kept the Singapore dollar nominal exchange rate stable during this period, backed by the full power of our reserves, giving banks and businesses certainty to make decisions under very trying circumstances," he said.
DPM Heng's experience during Asian, global financial crises
Mr Heng then related his personal experience during the Asian financial crisis in the late 1990s, when he was serving as principal private secretary to founding Prime Minister Lee Kuan Yew.
Mr Lee had been invited by several countries in the region to share his views, as the Singapore dollar, backed by the reserves, was relatively unscathed by currency devaluation crisis.
"It was very painful to see how speculation and the currency volatilities that those countries faced were destroying businesses, big and small, and the lives of the men and women in these places," said Mr Heng.
He noted that the Singapore dollar is one of the most actively traded currencies in the world relative to the country's GDP. The currency's daily turnover is estimated at US$37 billion (S$49 billion) globally, or annual turnover of US$9.5 trillion, far exceeding Singapore's nominal GDP of US$350 billion.
Compared with other countries, the exchange rate is far more important for Singapore, which is unique in its operation of an exchange-rate-centred monetary policy, noted Mr Heng.