(Bloomberg) -- Market watchers on Wall Street attribute this week’s stock selloff to the insidious threat of recession. Yet derivatives traders see a less ominous foe: the mass expiration of options on Friday — the biggest January event in a decade.Most Read from BloombergMore Young Americans Are Dying, But Not From VaccinesNew Zealand Prime Minister Ardern Announces Shock ResignationTreasury Taps Retirement Funds to Avoid Breaching US Debt LimitBiden Revives Housing Rule That Trump Derided as ‘