Shares in placements are very often offered at a discount to the last traded price to incentivise participation.
Companies often raise equity capital when they are acquiring a competitor or expanding operations. These transactions are called value accretive i.e. the company will be worth more after the event, than it was before the event.
Placements offered to fund a value accretive event can be attractive. Not only are the shares available at a discount to their last closing price, but a successful transaction can create a further increase in their underlying value.