Updated, 5:30 p.m. | You might think a man worth at least $5 billion would hardly notice if $400,000 or so went missing.

But someone noticed.

The Manhattan district attorney, Robert M. Morgenthau, announced this afternoon that two men had been charged with stealing or attempting to steal from personal financial accounts belonging to Mayor Michael R. Bloomberg.

One man, Odalis Bostic, was indicted for trying to steal $420,000 from the mayor. According to prosecutors, Mr. Bostic created the Laderman Development Company in Elizabeth, N.J., and set up accounts in the company’s name at two banks, PNC and Sovereign Bank.

In early June, Mr. Bostic deposited a $190,000 forged check into the Sovereign account and a $230,000 forged check into PNC account, according to prosecutors. Both of the forged checks were drawn on Mr. Bloomberg’s personal account at the Bank of America and were issued in the name of the mayor’s financial manager, Geller & Company.

The mayor’s personal account information appeared on both checks, but because of the size of the checks, the two banks put holds on the transactions. The banks determined that the checks were forged and then contacted the authorities.

Mr. Bostic, who was arrested in New Jersey in August and waived extradition, was to be arraigned today in State Supreme Court on a charge of attempted grand larceny in the second degree, a felony punishable by up to seven years in prison.

In the course of the investigation into the forged checks, an unrelated fraud was discovered, Mr. Morgenthau said.

A second man, Charles Nelson, has been charged with stealing $10,000 from one of the mayor’s financial accounts on May 11. In an online transaction, Mr. Nelson transferred $10,000 from the mayor’s Bank of America account to an E*Trade account the defendant had set up, prosecutors said. They said he later used a debit card for cash advances and to make purchases from the E*Trade account.

Mr. Nelson was arrested in Newark, and a computer, documents and two guns were recovered through search warrants. He remains in custody in New Jersey on local charges, but has been charged in New York with grand larceny in the third degree and identity theft in the first degree, both felonies punishable by up to seven years in prison.

Mr. Morgenthau credited Detective Drew Barone of the Police Department’s Special Frauds Unit and Christopher Romanyshyn of the New Jersey attorney general’s office for their work on the case. A Manhattan assistant district attorney, Jeremy B. Glickman, who is assigned to the Identity Theft Unit, was assigned to handle the prosecution.

A City Hall spokesman, John P. Gallagher, declined to comment on the matter.

This was not the first time criminals have gone after the mayor. Before he was elected in 2001, he helped officials build a case against a man from Kazakhstan who prosecutors say tried to extort money from Mr. Bloomberg’s financial services company, Bloomberg L.P.

Federal prosecutors said the man, Oleg Zezev, sent threatening e-mail messages in March 2000 to Mr. Bloomberg, in which Mr. Zezev said he had infiltrated the company’s computer system and wanted $200,000 in exchange, he said, for helping the company fix its computer security lapses.

Mr. Bloomberg contacted the F.B.I. and exchanged e-mail messages with Mr. Zezez. Eventually, he flew to London and met with Mr. Zezev, and an accomplice, Igor Yarimaka, who was also from Kazakhstan, in a hotel. The meeting was secretly recorded by police officers from Scotland Yard, using a hidden camera. In February 2003, Mr. Bloomberg testified at Mr. Zezev’s trial.

Mr. Zezev was convicted of extortion and sentenced to 51 months in prison. The charges against Mr. Yarimaka were dropped.