Sometimes, when legendary investor Warren Buffett starts selling a stock he just keeps on going, much like the Energizer bunny of advertising lore. That’s what’s happening now.

Recall that there are two sides to Buffett’s conglomerate Berkshire Hathaway  (BRK.B) . One side consists of private companies, such as Geico insurance and See’s Candies.

?? Free Newsletter From TheStreet - TheStreet ??

The other is comprised of big equity stakes in blue-chip companies. Many individual investors have prospered by mimicking those investments.

On the stock front, Berkshire owns more than 45 positions with a market value of $318 billion. That’s equal to 32% of Berkshire’s $1 trillion market capitalization. So these investments matter for the company.

Berkshire’s realized and unrealized gains on its stock holdings totaled $20.23 billion in the first half of this year.

Related: Veteran fund manager resets Nvidia stock price target after supplier update

But Buffett counsels against relying on this metric, as unrealized gains/losses don’t necessarily mean much for Berkshire.

Instead, he recommends focusing on its price-to-book value ratio, which totaled 1.66 as of Oct. 21, up from the five-year average of 1.39. Book value equals a company's assets minus liabilities.

Berkshire’s biggest holdings include:

1. Apple  (AAPL) , market value: $94 billion.

2. American Express  (AXP) , market value: $41 billion.

3. Bank of America  (BAC) , market value: $32 billion.

4. Coca-Cola  (KO) , market value: $28 billion.

5. Chevron  (CVX) , market value: $18 billion.

Buffett’s Bank of America machinations

Berkshire has been slashing its position in Bank of America since mid-July. Last week, Berkshire unloaded about $370 million of shares, in its 16^th round of selling.

Related: Warren Buffett's Berkshire sells bank stock before earnings

Buffett has now dumped more than $10 billion of BofA stock, pushing his stake in the company below 10%.

That’s important because investors with stakes above 10% must report their trades to the Securities and Exchange Commission within two business days rather than quarterly, as other institutional investors do.

Berkshire originally went below 10% earlier this month. But last week BofA announced it repurchased $3.5 billion of stock in the third quarter. That pushed Berkshire back above 10%.

BofA shares have dipped 4% to $42 since Berkshire began selling July 17. The KBW Nasdaq Bank Index gained 6% during that period. So Buffett’s moves may have convinced others to sell too.

He may have sold to take profit. BofA shares had soared 75% from last October until July 17. Berkshire also may be looking to push its stake in the bank below 10%, so that it doesn’t have to reveal its trades quickly.