The Yorkshire –based polyhalite miner is a cert to be included given that its market value currently of £1.2bn is almost double the average of those companies it will replace.
It will also cap a stellar rise for a company that a couple of year some doubted would ever make it off the drawing board given the complexity of the engineering work planned.
A successful US1.2bn fund raise last year to pay for the first phase of development however has transformed the perception of the project.
Indeed, one broker, Richard Knights at Liberum, who visited the site recently said the company’s chief marketing officer described the change of mood of potential offtake partners as “night and day” once they knew funding was arranged.
Knights added that a major offtake partner is what the shares need to push on further, but talks are underway with a number of potential of groups he said. Meanwhile, work has started to prepare the site at the mine.
Other first-timers joining Sirius in the FTSE 250 are likely to be aircraft lessor, airline and energy group Stobart Group Ltd (LON:STOB) with a market value currently of £991mln and giant US investment group Pershing Square Holdings.
Pershing is the vehicle of well-known US activist investor Bill Ackman, who has been in the news most recently for a disastrous investment in Canadian healthcare company Valeant that resulted in a 90% loss on his stake.