In a wide-ranging interview with Barry Ritholtz on Bloomberg’s Masters In Business podcast, Charles Schwab’s Liz Ann Sonders offers her take on the bull market, and a look at her early years working for the great Martin Zweig.

In the interview, Sonders talks about the importance of inflection points in the market, saying that the best gains start after the worst times. But investors often lose sight of the fact that the best time to invest is when the economic data is terrible and markets have been plunging, she says.

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Sonders says that, while the Federal Reserve’s policies have been a big factor in the six-year market rally, the Fed isn’t the only factor. Earnings growth has been in line with stock market growth, she says, for example. She also says that the biggest buyers during the bull run have been companies themselves, which have been consistently repurchasing their own shares throughout the bull.

Sonders also talks about her early years working for the great Martin Zweig. She discusses Zweig’s pioneering take on the relationship between monetary liquidity and the stock market, and his use of sentiment indicators before they’d become mainstream.