Apple co-founder Steve Jobs before his death last year. Apple today became the biggest US firm in history.
Apple has become the most valuable company in American history.
On Monday, its surging stock propelled the company's value to $623 billion, beating the record for market capitalization set by Microsoft Corp. in the heady days of the Internet boom.
Apple's stock has hit new highs recently because of optimism around what is believed to be the impending launch of the iPhone 5, and possibly a smaller, cheaper iPad.
Apple Inc. has been the world's most valuable company since the end of last year.
It is now worth 53 percent more than No. 2 Exxon Mobil Corp.
Apple's stock hit $664.74 in midday trading before retreating slightly to $663. That was $14.98, or 2.3 percent, higher than Friday's close.
Microsoft's 1999 peak was $620.58 billion, according to Standard & Poor's.
The comparison to Microsoft does not take inflation into account. In inflation-adjusted dollars, the software giant was worth about $850 billion on Dec. 30, 1999.
Microsoft is now worth $257 billion.
Analysts believe Apple's stock has room to grow. The average price target of 38 analysts polled by FactSet is $745.80.
Apart from the iPhone and 'mini iPad', analysts are speculating that Apple plans to make a TV set to complete its suite of consumer electronics products.
苹果公司已经成为美国历史上市值最大的公司。
本周一，苹果的股价一路飙升，公司市值涨至6230亿美元，打破了微软公司在网络迅速发展的激情时代创下的市值纪录。
苹果公司股价在近期创下新高，原因是人们对苹果被认为即将上市的两大产品——iPhone 5和可能体积更小、价格更低的iPad普遍持乐观的态度。
自去年年底以来，苹果公司一直是世界上市值最高的公司。
现在苹果公司的市值比第二名的埃克森美孚公司的市值多出了53%。
苹果的股价在午盘交易时达到664.74美元，之后略微下滑，降至663美元。收盘价格比周五收市时高出14.98美元，即2.3%。
根据权威金融分析机构标准普尔的数据，微软公司1999年的市值最高峰是6205.8亿美元。
这次苹果与微软的市值对比没有将通货膨胀的因素考虑在内。如果按通胀率做出调整，微软这一软件巨头在1999年12月30日的市值相当于今天的8500亿美元。
微软公司如今的市值为2570亿美元。
分析师认为，苹果的股价仍然有上涨的空间。根据金融分析机构FactSet的调查，38位分析师对苹果公司做出的平均估价为每股745.8美元。
除了iPhone和迷你iPad之外，分析师还推测苹果公司计划制造电视机，从而打造完整的消费电子产品系列。
market capitalization: 上市公司（股票等的）市值
heady days: 令人兴奋的日子