Amazon rallies 6.2% as most U.S. stocks climb

How much did Amazon gain?

Amazon shares surged 6.2% on Wednesday. They closed at $266.20, up from $250.69 at Tuesday's close.

Why it matters: The gain added $170 billion to Amazon's market value, the price of all its shares added together. That value now stands at $2.9 trillion. Investors traded $21 billion worth of the stock during the session. On $100,000 held in Amazon shares, the day added $6,180.

Why did the shares rise?

No Amazon announcement in the day's news explained the gain. CNBC's Halftime Report, a stock-picking show, named Amazon among its final trades. A pick on a cable show is an opinion, not company news.

The broader market may explain much of the move. The S&P 500, the index of large U.S. companies that many 401(k) funds track, jumped 1.6% to 7,688.62. The Dow surged 3.0%. Of 1,097 stocks tracked, 748 rose and 349 fell.

Most sector funds climbed too. The consumer discretionary fund surged 4.2%, and the financial fund surged 3.5%. The energy fund went the other way and tumbled 4.7%. In bonds, the 10-year Treasury yield fell 5 basis points to 4.90%.

What does Amazon's gain mean for an index fund?

Amazon makes up 3.2% of the combined value of the largest U.S. companies, a group worth $89 trillion. Its gain alone added $199 to $100,000 spread across those companies by size.

An S&P 500 fund added $1,580 on $100,000 for the day. Amazon's contribution was a small part of that total. Most of the day's gain came from other stocks. Funds tracking the tech-heavy Nasdaq-100 got a smaller lift, as that index rose 0.9%.

Is Amazon back at its high?

Not yet. Even after Wednesday, the shares sit 6.3% below their 52-week high of $284.02. A 52-week high is the highest price of the past year. A $1,000 stake bought a year ago would now be worth $1,068.

The open question is whether the gain says anything about Amazon itself, or only reflects a strong day for stocks. No company news so far settles it.

The next broad checkpoints are economic. Weekly jobless claims arrive Thursday, Nov. 5, at 8:30 a.m. ET. The October jobs report follows on Friday, Nov. 6, at 8:30 a.m. ET, and it could shape whether the wider rally holds.