LONDON — Turkey’s lira whipsawed in value again on Thursday, as the disclosure of a sudden drop in the central bank’s foreign reserves sparked fears among investors about the country’s economic stewardship.

The ailing economy is expected to be a primary concern among voters in local elections on Sunday.

The lira dropped as much as 5 percent against the United States dollar on Thursday before recovering to close up 2.4 percent, at 5.541 to the dollar.

But investors appeared to be worried about apparent efforts by the Central Bank of Turkey to shore up the lira’s value. Data released by the central bank on Thursday showed that its foreign exchange reserves dropped last week by $2 billion from the week before, to $71 billion, apparently reflecting efforts by the bank to purchase the currency.

Capital controls were put in place this week, preventing banks from lending to foreigners in an effort to keep the lira’s value up. Instead of providing reassurance, however, the move caused investors to worry that their cash would remain trapped in Turkey. That prompted many to sell their lira holdings for dollars, depleting the central bank’s reserves — which raised the specter of the bank’s running out of cash, prompting yet more selling.