Markets fall but US stock market rally may not be over

Markets fell on Monday.

In stock markets, the S&P 500 fell 0.5 percent after earlier losing as much as 1 percent. The STOXX Europe 600 fell 1.6 percent, with Greece’s ASE Index in particular dropping 4.7 percent.

The failure of Greece's debt talks weighed on investors' minds, with bond markets also affected.

Spain’s 10-year bond yields jumped 17 basis points to 2.41 percent. Portugal’s 10-year bond yields rose 22 basis points to 3.25 percent. Greece’s jumped 56 basis points to 12.32 percent.

Among commodities, copper fell 1.2 percent to a three-month low while West Texas Intermediate crude oil dropped 0.8 percent.

Notwithstanding the market declines on Monday, some analysts think that the US stock market rally is not over.

A recent report by the Royal Bank of Canada said that most bull markets end because the economy goes into recession. RBC thinks that currently, the risk of a recession is low.

John Higgins, chief markets economist at Capital Economics, told CNNMoney that he thinks the stock market is actually not very expensive and that "the market will track a sideways path; edging very slowly higher".

Higgins' comment comes even as the Wall Street Journal MoneyBeat blog reports that a method Warren Buffett once said was his preferred measure for evaluating the market is indicating that stocks are looking expensive.

Back in 2001, the legendary investor said that the “single best measure of where valuations stand” was the ratio of the value of publicly-traded companies in the U.S. to the country’s gross national product.

As of the end of the first quarter, the market capitalization of the companies listed on the New York Stock Exchange and the Nasdaq is about 150%, or 1.5, of GNP. By that calculation, the metric some have called the “Buffett Indicator” is now at its highest level since the dot-com era and above its historic norm of 119% over the past two decades.