NEW YORK — Amazon, the internet goliath that revolutionized the way much of the world buys books, toilet paper and TVs, hit a new milestone Tuesday. Its stock surpassed the $1,000 mark for the first time.That price put Amazon’s market value at about $478 billion, double that of the world’s biggest traditional retailer, Wal-Mart, and more than 15 times the size of Target. A $1,000 investment on Amazon’s first day of trading in 1997 would be worth more than $500,000 today.Not only has Amazon changed the retail landscape since it became a public company 20 years ago, it’s now part of a small cadre of high-flying stocks belonging to companies that have defied Wall Street and shunned stock splits.Those splits make the stock more affordable and generate brokerage fees. But companies like Amazon have chosen to reward its long-term investors.The last time Amazon has split its stock was nearly 18 years ago, according to financial research firm FactSet.Another company with a similar philosophy is Alphabet Inc., the parent company of Google.Amazon just beat Alphabet to the $1,000 level, with its Class A shares just $2 short of $1,000 Tuesday.Only four other U.S.-listed companies have shares trading above $1,000: online travel booking company Priceline Group Inc., homebuilder NVR Inc., pork producer and ocean transportation company Seaboard Corp. and the apostle of long-term investing, Warren Buffett, with his holding company Berkshire Hathaway Inc. But stock prices only tell a part of the story.The value of a company is determined by its stock price and the number of shares on the market. Amazon.com is well over four times the size of Priceline, NVR and Seaboard combined. It’s 17 percent bigger than Berkshire Hathaway, a multinational conglomerate with ownership stakes in some of America’s most well-known consumer brands like Coca-Cola, insurance companies and U.S. infrastructure.