S&P/ASX 200 Index (ASX: XJO) stock Washington H. Soul Pattinson and Co. Ltd (ASX: SOL) has just received major backing from one of its leadership figures with share purchases.

Robert Millner has been a non-executive director of the business since 1984, and the chair since 1998. Lewy Pattinson listed Soul Patts (as a pharmacy business) in 1903. Rob Millner is Lewy's great-grandson and is the fourth generation of the family to chair the company.

Millner recently increased his already-sizeable stake in the company.

It was announced yesterday that entities related to Rob Millner had bought a total of 520,000 Soul Patts shares between 2 April 2024 to 4 April 2024.

The first investment to buy 181,635 shares on 2 April 2024 cost $6.15 million, the second investment to buy 218,365 shares cost $7.33 million, and the third investment to acquire 120,000 shares amounted to $4.1 million.

Those three on-market trades cost around $17.6 million in total. Typically, insiders buying shares on the market may suggest they think the share price is good value.

By most people's standards, that's a huge investment and provides backing to the ASX 200 stock.

Millner's latest investments are large transactions, but they represent a small amount of his overall ownership of Soul Patts shares.

According to the ASX announcement, Millner now has a direct interest in 371,076 Soul Patts shares and indirect interests in 22,459,692 shares.

At the current Soul Patts share price, all of those shares are worth $783 million.

Interestingly, this investment was made just before the ex-dividend date for the interim dividend, which is the cut-off date for eligibility to receive the upcoming dividend.

The payout from the ASX 200 stock is going to be 40 cents per share – the ex-dividend date is 17 April 2024, so investors have until 15 April 2024 to acquire shares if they want a piece of that payout.

The business recently reported its FY24 first-half result, which came with two important positives. Soul Patts' net cash flow from its investments grew by 6.9% to $263.4 million for the six-month period – it uses this cash flow to fund larger dividends. The net cash flow grew thanks to continued growth of the credit portfolio and income from its strategic portfolio (where it owns large stakes in some businesses).

The HY24 pre-tax net asset value (NAV), meaning the underlying value, grew by 10% to 10.5 billion.

The ASX 200 stock's active management style aims to deliver returns that are better than the market.