Used vehicles have emerged as an unlikely top-performing asset, appreciating faster than major stock indices and even cryptocurrencies over recent months, according to market analyst Jim Bianco.

Citing the Manheim Used Vehicle Value Index, the Bianco Research President noted used car prices have surged more than 20% in the past four months alone—a rate exceeding the gains of both the S&P 500 and Bitcoin over the same period. Year-to-date, the index is up approximately 50%, a highly unusual move for a traditionally depreciating asset.

"This has all the tell-tale signs of a bubble," Bianco told CNBC's "Trading Nation." "Used car prices are supposed to be a depreciating asset. They're not supposed to go up in price."

He attributes the dramatic rise to two primary factors:

1. New Car Shortages: Consumers priced out of the new vehicle market, due to semiconductor shortages limiting production, are flooding into the used market.

2. Speculative Buying: A growing number of buyers are purchasing used cars with the intention of quickly reselling them for a profit, betting on continued price appreciation.

The trend is reflected in record-high average prices. In November, the average used car cost $27,569, a 27% increase from the previous year, while new car prices hit a record $46,320.

Bianco warns the phenomenon signals a broader inflationary problem that could complicate the Federal Reserve's policy outlook. "This is exactly what they don't want to see happen because this is that self-reinforcing idea about inflation," he said.

While predicting inflation will eventually slow, Bianco cautions the descent may be gradual. As for the used car market peak, he admits uncertainty: "This could go on for another year. It could go on for two more weeks. The activity that you're seeing is probably bubblicious."