Chinese e-commerce giant Alibaba Group (NYSE:BABA) stock had a rough year in 2021. As the Chinese tech stock market imploded, Alibaba shares shed roughly 50% of their value, costing outside investors in excess of $300 billion in stock market losses.

But this morning, Charlie Munger threw those investors a lifeline.

As Reuters just reported (and I rereported), the chairman of the Daily Journal Corporation (NASDAQ:DJCO) and vice chairman of Berkshire Hathaway just had the former of those two companies double its investment in Alibaba stock. In its second big purchase of the past year, Daily Journal scooped up 602,060 American depositary shares of Alibaba for about $36 million total.

Now why might Munger do something like that? It only takes a little quick calculator work to find the answer.

Even after today’s spike in share price, Alibaba only has about a $342 billion total market capitalization. Compare this to Alibaba’s $19.6 billion in annual profit — or even better, to its $24.1 billion in annual free cash flow — and it soon becomes clear that the stock is selling for a bargain price.

As of 12:10 p.m. ET, shares of Alibaba sell for about 17.5 times trailing earnings, or an even more attractive 14.2 times trailing free cash flow. Subtract the net cash on the company’s balance sheet — because according to S&P Global Market Intelligence data, Alibaba has $43.4 billion more cash than debt — and Alibaba’s cash-adjusted P/E ratio is just 15.2, and its cash-adjusted P/FCF ratio is an enticingly cheap 12.4.

Granted, there are risks to investing in China. And with most analysts warning that Alibaba will average only about 8% annual earnings growth over the next five years, it’s possible the Chinese tech giant’s best growth days are behind it. Still, at valuations these cheap, you’re not paying much for the risk involved in buying Alibaba shares.

This, in a nutshell, is probably why Charlie Munger has decided that Alibaba is a buy.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis — even one of our own — helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.