International stocks trading in New York closed lower on Monday.

The BNY Mellon index of American depositary receipts fell 2.9% to 143.12. The European index decreased 3.1% to 141.42; the Asian index dropped 2.5% to 150.58; the Latin American index fell 2.3% to 212.56; and the emerging-markets index declined 2.4% to 255.24. National Bank of Greece SA (NBG, ETE.AT) was among the companies with ADRs that traded actively.

ADRs of National Bank of Greece SA (NBG, ETE.AT) slid 24% to 97 cents amid Greece's worsening debt crisis. Over the weekend Greece decided to shut down its banking system for six days as the nation's central bank moved to impose controls to prevent money from leaving the country. On Monday, European leaders appealed to Greeks to vote "yes" in a referendum set for Sunday on measures demanded by its creditors in exchange for further aid. Athens also said it wouldn't make a loan repayment to the International Monetary Fund due Tuesday. Standard & Poor's subsequently said it sees a 50% likelihood of Greece eventually exiting the eurozone.

Among other European banks with declining shares, Deutsche Bank AG (DB, DBK.XE) fell 6.7% to $30.10, ING Groep NV (ING, INGA.AE) dropped 5.9% to $16.21, Lloyds Banking Group PLC (LYG, LLOY.LN) retreated 2.5% to $5.38, Barclays PLC (BCS, BARC.LN) decreased 3.6% to $16.50, Banco Bilbao Vizcaya Argentaria SA (BBVA, BBVA.MC) dropped 6.5% to $9.80 and Banco Santander SA (SAN, SAN.MC) fell 7.1% to $7.

AstraZeneca PLC (AZN, AZN.LN) says it is carrying out "detailed scenario planning ahead of the [Greek] referendum, including contingency planning for a potential Greek exit from the euro." The pharmaceutical giant makes $150 million to $200 million in annual sales to Greece, less than 1% of global revenue. A spokeswoman said the company was operating "as usual" in the country, "ensuring patients have access to important medicines." ADRs fell 3% to $64.34.

Novartis AG (NVS, NOVN.VX) said it acquired an Australian-U.S. drug developer that focuses on neuropathic pain treatments, expanding the Swiss pharmaceutical giant's pipeline of potential new products. Basel-based Novartis didn't provide financial terms of its deal for privately held Spinifex Pharmaceuticals Inc., which is jointly based in Melbourne and Stamford, Conn. Novartis ADRs fell 1.4% to $98.53.

ADRs of Petroleo Brasileiro SA (PBR, PETR3.BR, PETR4.BR) fell 4.1% to $9.03 after the Brazilian state-run oil company said it plans to slash investment by 37% over the next five years in an urgent effort to reduce debt and recover investor confidence amid a corruption scandal. In a long-delayed document outlining its five-year business plan, Petrobras also raised its asset-sale goal for 2015 and 2016, saying it now expects divestitures to reach $15.1 billion, from $13.7 billion previously. The company also cut it long-term oil production target.

Wowo Ltd. (WOWO) said its first-quarter loss narrowed thanks to stronger revenue that was more closely focused on the Chinese e-commerce platform's efforts to generate most of its sales from storefront fees. ADRs fell 5.3% to $8.37.

Write to Tess Stynes at tess.stynes@wsj.com

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