The Berkshire Hathaway (BRK.B) equity portfolio still holds many of the storied blue chips that most investors associated with portfolio. American Express (AXP). Coca-Cola (KO). More recently, Apple (AAPL) and Amazon.com (AMZN).

But a deeper dive into Warren Buffett's stocks reveals a more complicated picture, not to mention a portfolio that has undergone quite a few significant changes of late.

Most notably, Berkshire exited its investments in each of the four major U.S. airlines. The coronavirus pandemic, which put an end to the bull market, also decimated the airline industry. Buffett said as recently as March that he "won't be selling airline stocks," but in early May, Berkshire turned tail, disclosing in filings that it closed out its stakes in United Airlines (UAL), American Airlines (AAL), Delta Air Lines (DAL) and Southwest Airlines (LUV). And Buffett has done plenty more selling on top of that.

Berkshire Hathaway held positions in 43 separate companies (across 46 different stocks thanks to firms with multiple share classes) as of the end of the first quarter, down significantly from 49 in the fourth quarter. That's according to its most recent 13F regulatory filing, submitted to the Securities and Exchange Commission on May 15, as well as additional filings in May and April. But the portfolio of "Buffett stocks" isn't as diversified as the number might suggest. Some are new positions so small they equate to a pinky toe in the water. Other holdings are immaterial leftovers from earlier bets that the Oracle of Omaha has mostly exited, just not completely.

Still, anyone who wants to know which stocks legendary investor Warren Buffett feels are worth his time and attention need look no further than the Berkshire Hathaway equity portfolio. Just remember: A few of these Buffett stocks were actually picked by portfolio managers Todd Combs and Ted Weschler, who many believe are the top candidates to succeed "Uncle Warren" whenever he decides to step down.

Read on as we examine each and every holding to give investors a better understanding of the entire Berkshire Hathaway portfolio.

United Parcel Service

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United Parcel Service (UPS, $91.03), the world's biggest package delivery company, managed to survive a culling that claimed not only Berkshire's airline holdings, but also Philips 66 (PSX) and Travelers (TRV). Still, UPS remains the most meager of Buffett stocks. At fewer than 60,000 shares, this is a rump position, leftovers, an odd lot - and it's worth considerably less than it was just three months ago.

Buffett entered his UPS position during the first quarter of 2006, purchasing 1.43 million shares worth about $113.5 million at the time. That comes to an average price per share of $79.38. However, UPS never grew to be a major part of Berkshire's portfolio, and Buffett has pared the position over the years to where it wouldn't be a surprise if he exited the stake at any time.

While Buffett occasionally can be fairly chatty about some of his more notable stock picks, he typically doesn't comment on BRK.B's buys and sells. There's no mention of United Parcel Service in CNBC's indispensable Warren Buffett archive. But one clue as to why UPS never became a bigger part of Berkshire Hathaway's holdings might be its underperformance. Since March 31, 2006, UPS shares have delivered a total return (price plus dividends) of 73%; the S&P 500 Index generated a total return of 198% in that same time frame. That includes a miserable past year that has seen UPS decline 21% while the S&P 500 has lost 11%.

Translation: UPS has been a bust.

SPDR S&P 500 Trust ETF

He finally did it.

For years, Warren Buffett has been telling investors that one of the best ways to invest is to simply buy an S&P 500 index fund and keep a little something in Treasuries to help you sleep well in down markets. It's great advice; it just seemed a bit hypocritical coming from one of the market's most celebrated stock pickers. However, in 2020's final innings, Buffett finally took his own medicine and bought not one but two S&P 500-tracking exchange-traded funds (ETFs)

The first of those is the SPDR S&P 500 Trust ETF (SPY, $286.28), which tracks the 500 components of the S&P 500 Index. It does so for a song, too, costing just 0.095% annually, which comes to just $9.50 annually on a $10,000 investment. While many use it as a buy-and-hold investment, its high volume makes it a popular tool for traders, too.

It still makes little sense for a guy who's known for beating the S&P 500 handily over the long-term to buy a fund such as the SPY. After all, an ETF merely tracks an index, and will actually underperform slightly once costs are included. But it's possible that Buffett really wanted to drive his longstanding point home.

Vanguard S&P 500 ETF