The Bitcoin Misery Index (BMI) has fallen to its lowest level since 2011, sending a strong signal to investors that now is the ideal time to buy, according to Wall Street strategist and index creator Thomas Lee.

BMI Falls Below 20

The index recently touched a low of 18.8 on a scale of 1-100 where 27 is seen as an important indicator of bullish price action. That’s the lowest level since September 2011.

Lee developed the BMI as a contrarian indicator, which tells investors to buy when readings are low and sell when the headline figure is high. In an interview with CNBC last Friday, Lee said bitcoin has never failed to rise over the next 12 months each time the index fell below 27. By his count, BMI has fallen below that key level on four occasions, leading to a bullish year-long rally for the world’s biggest crypto asset.

In other words, BMI is telling investors that bitcoin is oversold, undervalued or a combination thereof.

Lee has a bullish outlook on bitcoin, telling CNBC that he is maintaining his mid-year price forecast of $20,000 and end-of-year target of $25,000.

Factors Behind the Drop in BMI

Bitcoin has been dragged through the mud in recent weeks by an outsized reaction to regulators’ comments on the digital asset class. This included an announcement by the U.S. Securities and Exchange Commission (SEC) that crypto exchanges must register with the agency to provide trading of so-called security tokens. However, this is largely consistent with the regulator’s treatment of initial coin offerings since last July when it deemed The DAO to be a security.

In reaching six-and-a-half year lows, Lee’s BMI plunged 24% from last Monday’s high. Prior to the decline, bitcoin looked poised to re-test $12,000.

“The BMI is telling us to keep the negative headlines in perspective,” Lee told CNBC. “When the BMI is at a ‘misery’ level, future returns are very good.”

Bitcoin is heavily influenced by news headlines and the market’s evolving perceptions about the legality of digital assets. Lee said this is unlikely to change anytime soon and that the next few weeks will probably be the most difficult for long-term investors. However, it is very likely that the market will turn a corner over the next three weeks.

Bitcoin prices peaked near $20,000 last December following a massive yearlong run that quickly spread to other digital assets. The coin lost some of its zeal in the new year as investors shifted their focus to the booming world of altcoins. Prices would later plunge below $6,000 as the crypto market shed two-thirds of its market cap.

Bitcoin traded around $9,100 on Tuesday for a market cap of $155 billion.