According to the Smart Finance APP, the Hang Seng Index company stated that as of November 24, the Hang Seng Index (referred to as 'HSI') officially marks its 55th anniversary. After 55 years of development, the HSI has become a benchmark reflecting the overall performance of the Hong Kong stock market, representing Hong Kong's market and capturing the evolution of its financial market. Currently, the HSI consists of 82 constituent stocks. As of the end of October, the market cap coverage and trading volume coverage reached 67% and 62% respectively. The top ten weighted constituent stocks account for approximately 56% of the index's weight. The financial industry has the largest weight, accounting for about 33%, followed by consumer discretionary (30%) and information technology (14%), with Hong Kong companies accounting for about 27% of the index's weight.

The HSI was officially launched on November 24, 1969.

The HSI was initially proposed to be established by Dr. Lee Quo Wei, former chairman of Hang Seng Bank, as an internal reference to measure the performance of the Hong Kong stock market. During its early stage, the HSI was updated once a day and proved to accurately reflect the market performance at that time. Subsequently, Hang Seng Bank decided to officially launch the HSI on November 24, 1969.

In 1969, when Hang Seng Bank launched the index, 33 stocks were selected as constituent stocks. Over the past 55 years, the HSI has undergone multiple reforms and enhancements, including increasing the number of constituent stocks to reflect the current market conditions, gradually raising the number of constituent stocks to 82 and continuing to expand market coverage.

The first significant change in the number of constituent stocks occurred in 2006, 37 years after the launch of the HSI. At that time, the HSI began to include stocks listed in Hong Kong as constituent stocks; as a temporary measure, the maximum number of constituent stocks was increased to 38. In 2007, the number of constituent stocks reached 38, with the maximum further increased to 50 to ensure that the HSI continued to be made up of the largest and most liquid stocks in the Hong Kong stock market, becoming one of the most representative market benchmarks.

The maximum number of constituent stocks remained at 50 until 2020, after which the HSI underwent a comprehensive review; in 2021, a recent significant optimization was carried out. After exploring the composition of constituent stocks, stock selection, number of constituent stocks, weight, industry, and regional representation, the number of constituent stocks increased to a final target of 100.

Since the launch of the hang seng index, only four companies have maintained their status as constituentstocks in hang seng index.

Since the launch of the hang seng index, the constituentstocks in hang seng index have undergone regular adjustments to reflect the importance of different sectors and to closely align with the increasingly tighter economic ties between Hong Kong and the mainland. With Hong Kong listed companies undergoing mergers, acquisitions, and privatizations in the market competition, many constituentstocks have changed over time. Of the 33 constituentstocks when the index was launched in 1969, only 4 remain as constituentstocks (as of the end of October 2024): clp holdings limited (00002), hk & china gas limited (00003), hsbc holdings limited (00005), and power assets limited (00006).

In 2023, the hang seng index was repositioned to reflect the overall performance of the Hong Kong stock market.

Over the past few decades, the hang seng index has undergone multiple rounds of reform and enhancement, all aimed at maintaining market representativeness and capturing the evolution of the Hong Kong financial market.

The first significant enhancement of the hang seng index occurred in 2006, when the index calculation method began to change from full market cap weighting to free float adjusted market cap weighting, and H shares were included for the first time, resulting in a change in the number of constituentstocks since its launch. Another major change took place in 2021, with enhancements including setting the maximum number of constituentstocks to 100 to improve market coverage and selecting constituentstocks from seven major industry groups to expand industry representation.

In addition, after expanding the eligibility criteria for constituentstocks to major foreign companies listed in Hong Kong, the hang seng index has repositioned itself from representing greater china companies listed in Hong Kong to a more comprehensive benchmark representing the overall Hong Kong stock market.

A comprehensive product ecosystem has been built around the hang seng index.

Over the past few decades, the hang seng index has evolved from an internal reference indicator of hang seng bank to a globally recognized benchmark for the Hong Kong stock market, forming a comprehensive product ecosystem around it.

The hang seng index is used as a base index for various derivative products. The hang seng index futures were launched in May 1986, followed by the hang seng index options in March 1993. Since then, these derivative products have attracted an increasing number of domestic and international investors. For example, in the first 10 months of 2024, the trading volume of hang seng index futures and mini hang seng index futures accounted for nearly 35% of the total futures trading volume in Hong Kong.

Including exchange-traded funds (ETF) and leveraged and inverse products (L&I), the number of exchange-traded products (ETP) tracking the hang seng index has increased to 15 since the launch of the first ETF tracking the hang seng index (also Hong Kong's first listed ETF) in 1999. As of the end of October 2024, the total assets under management reached 25 billion dollars.