It’s the Weirdest Time in History for Finance. What to Know About Bubbles in Cryptos, Meme Stocks, and NFTs.

Two days after Halloween, there were more costumes than usual in New York’s Times Square. Outside Jimmy Buffett’s Margaritaville restaurant, one man wore a mirrored face shield and knit beanie to resemble a CryptoPunk pixelated character. A vehicle transformed to look like a cockroach made from junk played a slow-speed rap about “stacks of cash” to market a digital art gallery. A cowboy crooner in underpants, himself as familiar as a pretzel stand to regular passersby, had been commissioned by a man and woman in matching onesies to sing about their holographic worm.

This...