Apple (AAPL) stock hit yet more record highs Thursday, as the announcement of a new iPhone and the Federal Reserve's plans for economic action boosted the shares of the most valuable company in U.S. history.

Apple shares moved as high as $685.50 in Thursday's session, and ended the session with a record closing high of $682.98 after a 2 percent gain. Apple had previously set a record intraday high of $683.29 Monday after establishing a record closing high of $680.44 Friday.

Apple shares originally moved higher Thursday morning after the Cupertino company's Wednesday event, during which CEO Tim Cook and other executives unveiled the newest iteration of its iconic smartphone, the iPhone 5, and other updates expected to boost Apple sales through the end of the year. Pre-orders for the iPhone 5 begin Friday, with the first devices arriving Sept. 21.

While analysts said the new iPhone lacked a "wow factor," it will be the fastest and lightest Apple smartphone yet and have a bigger screen -- 4 inches rather than 3.5. The technical advances led Apple Senior Vice President Phil Schiller to call it "the most beautiful device we've ever made."

"While it lacked the mind-blowing innovation we have come to expect of Apple, (the iPhone 5) is differentiated enough

Analysts were more focused on what the iPhone 5 release could do for Apple's bottom line Thursday, and they were bullish on the aggressive launch schedule -- the iPhone 5 is set to debut in eight other countries besides the United States on Sept. 21, more foreign countries on Sept. 28 and a planned 100 countries by the end of the year. The general consensus was spectacular sales results for the current quarter and the holiday-shopping period.

"We are positively surprised that this iPhone rollout is Apple's fastest yet," Barclays Capital said in a note. "Given this pace, it would seem Apple is very well positioned for upside in the December quarter."

After the announcement, brokerages increased their estimates for iPhone sales in the current quarter as much as 36 percent, increasing their estimates to as many as 33 million sold. The increased forecasts for sales of Apple's most profitable product also led to increased price targets -- the price at which an analysts believes an investor should sell shares for maximum return -- ranging from $750 to $1,000.

Shares got an additional boost to their record levels Thursday afternoon after Fed chairman Ben Bernanke announced the U.S. central bank would begin an open-ended campaign of buying bonds to juice the economy, which sent the market soaring higher. All three major U.S. indexes increased by at least 1.3 percent, and the SV150 index of Silicon Valley's largest tech companies moved up 1.6 percent.

Apple's stock price has risen substantially in 2012, thanks to tremendous sales numbers for iPhones and iPads, pushing the company to a record for market capitalization for a U.S. company, without adjusting for inflation. At Thursday's closing price of $682.98 share price, Apple's market cap -- the total worth of all shares in circulation -- was $640.2 billion.

Reuters contributed to this report. Contact Jeremy C. Owens at 408-920-5876; follow him at Twitter.com/mercbizbreak.