Markets fell on Monday following last week's failure to resolve the Greek debt crisis and as the country shut lenders and imposed capital controls.
The S&P 500 fell 2.1 percent while the STOXX Europe 600 fell 2.7 percent. Yields on US 10-year Treasuries fell 15 basis points to 2.33 percent while yields on 10-year Greek bonds surged 423 basis points to 15.08 percent.
The euro fell against the yen but managed to recover from early losses against the US dollar.
While Monday's decline left the S&P 500 down 0.1 percent for 2015, Mark Hulbert says that Greece by itself is too small to have much impact on the global markets.
Ron Insana agrees, but points out that with China's stock market tumbling, Puerto Rico also having debt repayment problems and the Federal Reserve poised to raise interest rates, there is still a risk of "a summer of discontent for equity- and bond-market investors".