A more than 100-year-old buy signal just flashed in the stock market

• A more than 100-year-old buy signal just flashed in the stock market, according to LPL Research.
• Dow Theory is based on the relative price action of the Dow Jones Industrial and Transportation averages.
• The buy signal suggests there is plenty of more upside ahead for the stock market, according to LPL.

A classic stock market buy signal called the Dow Theory just flashed, according to LPL Research, suggesting that there is more upside to be had in the current rally.

LPL’s chief technical strategist, Adam Turnquist, highlighted in a Friday note that expanding participation in different areas of the stock market helped catapult the Dow Jones Transportation Average to new 52-week highs last week, confirming the broader rally in the Dow Jones Industrial Average.