"The key focus is increasing awareness that investing is accessible. How can we encourage more and more people to try it while becoming a loved and trusted household brand."
Roberts said Trade Me saw the investment in Sharesies as a way to add value to its ecosystem while helping the technology start-up to get the capital needed to scale and grow.
The business has just hired its 14th employee and plans to add another three people soon.
"That will take us up to 17."
Brooke said she saw Trade Me as the place where people bought their dream car or house while Sharesies was where people could invest for the future so they could afford that dream.
Companies Office records show Trade Me is now the biggest shareholder in the start-up company although Brooke and co-founder Leighton Roberts have just under 22 per cent between them.
Roberts said while the Trade Me investment was the largest holding, it was still a minority shareholding.
Longer-term, whether that investment went further would depend on what was right for Sharesies, Roberts said.
"There are so many opportunities for Sharesies."
As to listing itself, Roberts said: "We definitely have that as an option."
She said the company had prepared for that in the future by having audited accounts. But it was not something on its immediate time horizon.