In the early 1970s, brothers Nelson Bunker Hunt and William Herbert Hunt (heirs to a Texas oil fortune) began accumulating silver massively as a hedge against high inflation after the end of the gold standard (1971). They bought physical silver (bullion) and futures contracts on COMEX, eventually controlling about 200 million ounces—more than half of the world's private supply at the time.
This drove the price of silver from ~$6/oz in early 1979 to a peak of $49–50/oz on January 18, 1980 (an increase of over 700%). At its peak, their positions were worth billions in paper gains, creating a real shortage and a "silver fever."

The Collapse: March 27, 1980
Regulators then intervened: in January 1980, COMEX adopted Silver Rule 7, restricting leveraged purchases and position limits. The brothers, heavily indebted, were unable to meet margin calls.

On March 27, 1980, the price fell more than 50% in a single session, from about US$21/oz to US$10.80/oz — the largest daily percentage collapse in silver history at the time.

This caused panic in the markets, affecting even stocks and other precious metals.

Consequences:
The brothers lost approximately US$1–1.7 billion, received a US$1.1 billion bailout from banks to prevent a systemic collapse, but declared bankruptcy in 1988.
They were convicted of market manipulation: they were fined approximately US$10 million each, plus US$134 million in civil damages, and they were banned from trading commodities for life.
The event led to regulatory reforms at COMEX and CFTC, including stricter position limits.
To this day, Silver Thursday is a classic example of extreme leverage risk-taking, attempting to corner the market with subsequent regulatory intervention—this is often compared to modern squeezes, but unique for the scale it had at that time.