The Arora family has sold 40m ordinary shares in the B&M business for over £200m.
An announcement to the markets on Monday afternoon said SSA Investments, the Arora family's investment vehicle, wanted to sell the shares by way of an accelerated bookbuild to institutional investors.
The placing shares represented around 4% of discount chain B&M's issued share capital.
Early on Tuesday, a second announcement said the shares had now been sold for 545p each - raising a total of £218m.
SSA Investments had owned around 150m ordinary shares - a 15% stake in B&M - which has now been reduced to 10.98%.
Merrill Lynch International acted as global coordinator, while Rothschild & Co was the sole financial adviser.
Both announcements came from Merrill Lynch International, and said the bookbuilding period began on Monday - and could "close at any time on short notice".
B&M will not receive any proceeds from the secondary placing, it said.
