The P/E doesn't mean it's overvalued, it means it's priced assuming substantial growth in earnings. That doesn't make either the forward-looking market price or

The P/E doesn't mean it's overvalued, it means it's priced assuming substantial growth in earnings. That doesn't make either the forward-looking market price or the backwards-looking profit numbers wrong. If that growth is unlikely to happen, then it's overvalued. If Twitter becomes quadruple-Facebook and is earning $2.5 billion/year in a few years, it's very undervalued.