Palantir Technologies stock closed at a record high Thursday and was gaining again in trading Friday.On Thursday, shares of the provider of data-analytics software rose 4.7% to $39.24, notching a record,

Furthermore, Palantir's market cap has risen to $82 billion. A 100-fold gain in the stock would take the market cap to $8.2 trillion. This is about 2.3 times the $3.4 trillion market cap of Apple, the current market cap leader. That shows the extent of how much Palantir is going to have to grow to make millionaires out of small investors.

But that premise doesn't in and of itself make Palantir stock a buy. Valuation always matters in investing, and investors need to be clear about what expectations have been priced into Palantir's shares after their impressive surge. PLTR Revenue (TTM) data by YCharts.

Palantir Technologies shares moved higher Monday. The stock joined the S&P 500 as part of the index's quarterly rebalancing.

Shares of Palantir (NYSE: PLTR) ripped 18.2% higher in September, according to data from S&P Global Market Intelligence. The software and artificial intelligence (AI) platform for the military and big business joined the S&P 500 (SNPINDEX: ^GSPC) index,

While Palantir has lots of opportunities in the AI market, there are two reasons I think Microsoft's stock is the better option. First, it's far less expensive than Palantir's shares.