(CNN) — South Korean semiconductor giant SK Hynix became one of the few companies in the world with a $1 trillion market cap this week, as a global AI boom continues to propel chip stocks to record levels. The memory chip maker’s rise follows that of its competitors: Samsung Electronics and Micron, a US semiconductor manufacturer which also hit $1 trillion earlier this week. The three companies combined account for nearly all of the world’s production of memory chips.