Gold has "decoupled" its century-old relationship with oil and is now being driven by interest rates and currencies, according to Bank of America/Merrill Lynch Tuesday.

"Moreover, we think that a unique combination of factors is again making gold attractive in investor portfolios: negative nominal interest rates, a closing volatility gap to other asset classes, and improving weekly returns. After all, unlike government bonds or fiat currency, gold is no one's liability," said BoA/ML analyst Michael Widmer.