Investors buy and sell about 5 million Target Corp. shares on an average day. In just the first hour of trading Wednesday, they traded nearly 20 million.

That is only one reason Wednesday was an exceptional day for Target on the stock market.

The company's stock raced upward more than 20%, its largest single-day gain in its history. Two hours into the trading day, Target shares were trading at $101.87, up from Tuesday's closing price of $85.53. The stock closed Wednesday at $103. Broad market indexes were up about 1%.

At least three investment analysts had published reports projecting that Target's share price would exceed $100 within a year. But the mean estimate among 27 analysts following the company was $89.13.

Target's previous record one-day gain was 17.8% on Oct. 28, 2008, just weeks after the mid-September market collapse and start of the last recession.

Target at the time was in a battle with activist investor William Ackman, who promised on that day to unveil a potential transaction that would boost the value of its real estate holdings. Target shares jumped from $24.27 to $28.58, lifting the company's market capitalization to around $23 billion.

By the end of the recession in early 2010, Target shares had surpassed $50 and have never fallen below that level since.

With Wednesday's huge jump, Target's shares were priced nearly four times higher than they were in 2008. But its market capitalization is little more than two times higher. The company, like many U.S. firms, has frequently repurchased shares since the recession, reducing the base that's part of the equation for calculating market value.

Wednesday's gain pushed Target's market capitalization above $50 billion for the first time. It ended the day worth nearly $52.8 billion.

By revenue, Target is the second-largest publicly traded firm that's based in Minnesota. Its annual sales will be $75 billion to $80 billion this year, trailing only UnitedHealth Group, which exceeds $200 billion in annual sales.

In market capitalization, Target is the sixth-largest company based in Minnesota. It trails UnitedHealth at $227.6 billion, Medtronic at $143 billion, 3M at $93 billion, U.S. Bancorp at $81 billion and Ecolab at $59 billion.

Patrick Kennedy • 612-673-7926 Evan Ramstad • 612-673-4241