Former Federal Reserve Chairman Alan Greenspan said stock market momentum is heading upward.

“In a sense, we are actually at relatively low stock prices,” Greenspan, who guided the central bank for more than 18 years, said in an interview with Sara Eisen on Bloomberg Television.

“Indeed I say that so-called equity premiums are still at a very high level, and that means that the momentum of the market is still ultimately up.”

The Standard & Poor’s 500 Index advanced 23.03 percent this year through yesterday, pulling within a percentage point of its 23.5 percent surge in 2009, amid speculation the Fed will delay cuts to its monthly bond purchases until the labor market improves.

The benchmark index rose 0.6 percent Tuesday to a record, before wiping out the gain and falling to 1,744.03 at 10:25 a.m. in New York.

Greenspan, 87, also praised Fed Vice Chairman Janet Yellen, whom President Barack Obama has nominated as the next head of the central bank, both in the Bloomberg interview and in an earlier interview on CNBC.

“She’s a very bright lady,” Greenspan said of Yellen on CNBC. “I think she will surprise everybody, I mean in a positive way.”