Can my percentage ownership be diluted? If yes, when and how?

Yes. Any investment made through truCrowd may be subject to dilution in the future. Dilution occurs when a company issues more shares. Dilution affects every existing shareholder who does not buy any of the new shares being issued. As a result, an existing shareholder's proportionate shareholding of the company is reduced or 'diluted'- this has an effect on a number of things including voting, dividends and value.
 
Some businesses who pitch through truCrowd offer A-Ordinary Shares, which may include pre-emption rights that protect an investor from dilution. In this situation the business must give shareholders with A-Ordinary Shares the opportunity to buy additional shares during a subsequent fundraising round so that they can maintain or preserve their shareholding. Please research the pitch and the Articles of the company to see if the shares you are buying will have these pre-emption rights. Most companies do not offer pre-emption rights for B Investment Shares.