Last weekend, news showed that stock god Buffett unexpectedly sold a large amount of Apple stocks in the second quarter, which led to a "Black Monday" for Apple's stock price and even the entire US stock market in the following trading day.

But in fact, Buffett's sale brought some unexpected good news to Apple investors: the influence of Apple in major stock indices will be fully unleashed.

For many years, Apple's weight in a series of benchmark indices has been low because Buffett's Berkshire Hathaway prefers to hold its investment for the long term, making it impossible to trade that part of the shares. As a result, index providers calculate Apple's weight according to a method called market capitalization adjusted for floating shares. Therefore, Apple's true weight has not been reflected in many indices.

In percentage terms, these figures don't seem to be large. For example, in the S&P 500 index, Apple's market value is currently accounted for 94%. But investment banks and institutional securities company Piper Sandler believe that this number should now rise to 100%. For a company with a market cap of $3 trillion, this gap is not insignificant.

According to Piper Sandler's estimate, when the passive index funds that track related indices rebalance next time after Berkshire sells its Apple holdings, they may have to buy up to $40 billion worth of Apple's stocks, which is three times the average daily trading volume of the company's stock in the past month.

According to Piper Sandler's above calculation, the entry of passive funds can fill a considerable proportion of Berkshire's exit. As of the end of the second quarter, Berkshire's Apple stock holdings were valued at $84.2 billion, and Apple's holdings in the second quarter fell from 0.789 billion shares in the first quarter to about 0.4 billion shares.

Passive index funds rushing into the market have been criticized by David Einhorn, founder and president of long-short hedge fund Greenlight Capital, who believes that passive investing fundamentally undermines the market by making so much money insensitive to value.

Some analysts believe that Buffett's halving of his holdings in Apple shows a lack of confidence in the company's growth prospects, and Buffett has shown significant sensitivity in valuation.

Apple has also received some negative news this week. A US court ruled that Google's search business violated US antitrust laws. To maintain its position as the default search engine, Google pays Apple a huge sum of money every year. If Google loses the case, Apple's operating profit may be affected up to about 17%.

It should be noted that the rise in Apple's weight is bad news for some other companies in the index, as their weight will be reduced to adapt to this change and their stocks will be sold by passive index funds.

The first revision of Apple's weight will take place when the quarterly indices are rebalanced next month. At present, the market is more focused on US economic growth and the Federal Reserve's monetary policy. Nonetheless, a group of traders are betting on events such as weight adjustments affecting stock prices. Piper Sandler's chief investment strategist said, "We often see trading activity because of rebalancing. People want to know this."

A spokesman for S&P Dow Jones Indices declined to comment further on the weight adjustment.

This week, Apple's stock price showed a trend of first suppressing and then rising. Although the low point on Monday when the US stock market collapsed was more than 10% lower than Friday's closing, the daily closing decline narrowed significantly, falling only 4.8%, and the cumulative decline this week was only 1.65%.

Editor/Emily