This is a pretty speccy buy. Brokerage is pretty sticky business. People have to actually be bothered to change to their system, which could take some convincing. It's an entirely new platform for starters. They will have more success attracting first time investors, rather than stealing customers from other services, because the savings aren't that huge at the levels most people trade at. CMC charge $11 per trade at their lowest bracket, for example, which is only a $1.50 difference per trade. (i'm with CMC, and I can't be bothered for that amount - particularly since CMC are now offering international share brokerage, and I didn't even need to do any paperwork).
Given their heavy investment in marketing, and their executive team (which is quite large), they will require a pretty large customer base to break even, which will take some time. I expect they will need another capital raise or two before they really build tangible momentum.
Buuut .... SOL (a substantial shareholder) are not silly. I have a small holding. *Update - SOL have since sold their holding.
Update Sep 2018 - Following their financial results release, they state they are taking a 10% market share for new traders to the market. This is a little disappointing, as they have a significant marketing budget and the lowest price point in the market - and also because they are not making any significant inroads to take established market share from competitors. Growth figures look impressive, but to be successful, they will have to gain traction at a much higher rate in this next reporting period.
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Update Aug 2019
Latest results announcement showed that the platform is gaining traction, and their marketing spend and cost of acquisition has improved significantly. Their margins are around 35% on current numbers, which is not good enough to outpace the spend required to grow - and they're not growing fast enough for their revenue to cover costs before requiring another capital raise. Suggest waiting for the next capital raise before investing, but long term their strategy is sound, and they have earned their place in the market as a platform.