"Bad breadth" in the stock market happens when a few big companies drive most of the market’s gains while the majority of stocks underperform. It’s a warning sign that the market’s strength might not be as solid as it seems. Here are some key examples:

1. Dot-Com Bubble (Late 1990s - 2000)

In the late '90s, tech companies like Microsoft and Cisco pushed the market up, but most other stocks struggled. When the bubble burst in 2000, the whole market crashed.

2. Financial Crisis (2007-2008)

Before the crisis, a few big banks and housing stocks were doing well, hiding weaknesses in the rest of the market. When the housing bubble popped, the market tanked.

3. Energy Crash (2014-2015)

Tech and healthcare stocks kept the market looking strong, but energy stocks collapsed due to falling oil prices. This imbalance signaled trouble.

4. Tech Dominance (2018)

The market relied heavily on tech giants like Apple and Amazon (FAANG stocks). When they stumbled, the entire market wobbled by the end of the year.

5. Pandemic Rally (2020)

After COVID hit, big tech stocks like Amazon and Tesla carried the market higher, even though most other businesses were struggling.

6. AI Boom (2023)

In 2023, stocks tied to AI—like Nvidia and Microsoft—drove most market gains. Other sectors barely moved, raising fears of overreliance on a few winners.

Why It Matters

When only a few stocks or sectors are performing well, it makes the market fragile. If those leading stocks falter, the whole market can tumble, which is why bad breadth often signals potential trouble ahead.