Protection against price drops in BlackRock's spot bitcoin BTC$115,288.35 exchange-traded fund (ETF), is now at its priciest since the early April market slide.On Monday, the spread between implied volatilities (IV) for 25-delta puts and 25-delta calls for the iShares Bitcoin Trust ETF (IBIT) rose to 4.4, the widest since April 10, according to data source Market Chameleon. In other words, put options, which insure the buyer against price drops in the underlying asset, traded at a premium of 4.4 IV relative to calls, or bullish bets. It's a sign investors are increasingly seeking protection against price declines, reflecting growing concerns about IBIT's near-term outlook. IBIT gapped lower at $65.72 on Monday, tracking overnight losses in the spot bitcoin market. At press time, the ETF shares were trading at $65.44, down 1.51% for the day, having reached a record high of $69.89 last week, according to data source TradingView.