SHANGHAI — Chinese economic policy makers tugged back the curtain a bit on Thursday on their plans to stabilize the country’s economy and financial markets, even as shares plunged more than 6 percent late in the day.

Speaking to leaders of the world’s biggest banks and institutional investors at a financial conference here, officials described how they would use government deficit spending to spur growth. A senior Chinese central banker also pledged to preserve the value of China’s currency, the renminbi, by firmly tying its value to a range of other currencies.

Timothy Adams, the chief executive and president of the Institute of International Finance, said Chinese policy makers realized they had made a serious mistake by staying silent as slowing growth, stumbles in the stock market and a fluctuating currency undermined the world’s perception of China’s economic stability. Their silence has been widely construed as either a reluctance to acknowledge difficulties or a lack of solutions.

“Either they communicate with the markets in a timely and intelligent fashion, or the markets are going to write their own story line,” said Mr. Adams, a former senior United States Treasury official.

Finance ministers and central bank governors from around the world are flying into Shanghai for meetings this weekend. Global banking leaders are already here for the annual conference of the Institute of International Finance. So a large contingent of Chinese officials has come from Beijing to meet with them and discuss their policies.

So far, the Chinese officials have acknowledged the challenges they face, but they contend that the world has overlooked the many policy options they can use to respond.

The officials outlined how they hoped to shift the economy from its emphasis on manufacturing, exports and a sometimes manic pace of construction, toward services and consumer spending. And they described how they hoped to manage that transition without tripping up economic growth along the way.

Zhu Guangyao, a vice minister of finance, said Thursday morning that Prime Minister Li Keqiang would unveil a government budget early next month that would include economic stimulus through an increase in deficit spending, which was only 2.3 percent of economic output last year. “In 2016, certainly we will have to increase that ratio,” he said.

Although China’s corporations are heavily indebted, the Chinese central government is not.

In a subsequent speech to international bank leaders, Yi Gang, the first deputy governor of the People’s Bank of China, provided the strongest commitment to date not to devalue the renminbi. He described a complex strategy based on anchoring the value of the renminbi to three baskets of currencies. The baskets are essentially weighted averages of how much the renminbi is worth in terms of dollars, euros, yen and other currencies.

Zhou Xiaochuan, the governor of the central bank, is scheduled to speak Friday morning and then hold a rare news conference immediately afterward.

He will have much to discuss: Money has been sluicing out of China this winter, as companies and individuals use their renminbi to buy dollars, fearing that the renminbi may decline further against the dollar. As officials spoke on Thursday, the Shanghai stock exchange on the other side of town was sliding steeply, ending with a loss of 6.4 percent — a particularly precipitous decline given that the market halts trading in any listing once it has fallen 10 percent.

Share prices slid on Thursday, not in response to the reassurances of Chinese officials but rather to a spike in short-term interest rates in Chinese money markets.

Despite huge outflows in recent months, it was not immediately clear that trying to slow them was the sole cause of the rise in interest rates. The Chinese central bank injects huge sums of cash into the economy in late January and early February each year in anticipation of heavy consumer spending during Chinese New Year, then tries to drain some of that extra money in late February. It is a tricky task every year, and especially when financial confidence is weak.

Even if Chinese officials do start unveiling further policy responses to economic weakness, it is unclear whether overseas investors will believe them. China has repeatedly promised measures to limit the rapid growth of corporate debt and to overhaul state-owned enterprises, notably at the Third Plenum, a policy-setting gathering in the autumn of 2013. But putting changes in effect has proved slow and difficult, as many could involve layoffs in single-company towns with few alternative employers, and could threaten the livelihoods of politically connected executives at troubled state-owned enterprises.

The Chinese central bank has been trying to inject additional cash into the economy to offset outflows and prevent interest rates from rising. Qu Hongbin, the chief economist for greater China at HSBC, said that not all of the money leaving China was harmful, however. He estimated that three-fifths of it consisted of Chinese companies paying overseas debts, which would become more expensive in renminbi terms if the currency weakens further.

Mr. Yi, the deputy governor, sought to reassure bankers that China’s central bank would not tolerate another broad decline in the value of the renminbi. The bank devalued the renminbi 4 percent compared with the dollar last August, then pushed it down nearly 3 percent in late December and early January.

Mr. Yi said that China is anchoring its currency to three weighted averages of currencies: one that it calculates itself, one from the Bank of International Settlements and one from the International Monetary Fund. Paul Gruenwald, a former I.M.F. official who is now the Singapore-based Asia economist for Standard & Poor’s, said that because the dollar typically makes up a third of each of these baskets, the shift meant that the renminbi could conceivably vary three times as widely against the dollar.

The renminbi gained against the broader baskets through much of last year, even as it weakened against the dollar. But this winter, the currency has also weakened against the averages, as it has followed the dollar down against the euro.

By not specifying which of the baskets is most important, the People’s Bank of China keeps greater flexibility, although at the cost of also allowing greater uncertainty in financial markets. China’s own basket includes currencies that are somewhat important for its trade, like the Russian ruble and Malaysian ringgit. The I.M.F.’s special drawing rights, another basket cited by Mr. Yi, only has the dollar, euro, yen, British pound and the renminbi.