Key metric tied to BlackRock's Nasdaq-listed spot bitcoin (BTC) exchange-traded fund, IBIT, has been flashing warning signs for two straight months. IBIT's one-year put-call skew, a measure of market sentiment or pessimism, flipped positive on July 25 and has remained comfortably above zero since then, according to data source Market Chameleon. That's two straight months of bearish put bias. In other words, traders have consistently favored protective puts over bullish calls for two months, signaling a s ...