Investors usually look at the advance-decline line to gauge if a trend is still healthy. In theory, an up-trend is healthy if advances by an index are supported by most stocks (opposed to being driven by only few advancing stocks while the majority is already in decline). Every day you add the number of advancing stocks and subtract the number of declining ones (the absolute value does not matter). Currently it looks as if the uptrend is supported my the majority of stocks. We are using the NASDAQ (NYSE has too many bond-like ETF’s listed blurring the picture).