Convertible notes are a way to invest money now (the 'note') at a valuation that will be decided later (at 'conversion'). It is mostly used by angel investors to invest in very young startups for which it is too hard to put a valuation on them. The conversion of the convertible note debt into equity happens at series A investment by venture capitalists. Often the convertible note holders get a discount on the valuation, to compensate for putting in their money earlier. There may also be time limits on the conversion or a cap on the valuation.
Example: Angel invests $500K in startup in convertible note form, startup raises 10M from venture capital firm at 90 million pre-money valuation later. The VC firm ends up with 10% of the equity, because 10 million is 10% of 100 million post-money valuation (90m pre + 10m invested). The angel will receive 500K / 100 million = 0.5% of equity if there is no cap or discount. If there is say a 50% discount, the angel gets 500K / 50 million = 1% equity so double the equity. Same effect would be if there is a cap of the conversion valuation at 50 million, i.e. no matter what valuation the VCs invest at the angel gets at least 1% of equity because 500K / 50 million = 1%.
This is a great and concise description. So in effect, are the terms on convertible notes just bets on the following round's valuation? In that case, it seems to me that's not much different from valuing the company right now, because if you have enough information (from projections & standard multipliers for the industry/sector) to bet on the A round's valuation, you could just interpolate a valuation at the current time...
I'm starting to realize that my gut reaction to squint skeptically at convertible notes wasn't too far off the mark... it's like going to Vegas and betting your company, but everyone else at the poker table has been playing for years longer than you have...
Convertible notes are a way to incentivize great execution by the founder team between the angel round and the series A. Execute better => Higher series A valuation => Less dilution from the convertible debt.
At the angel stage there are very little metrics and multiples to go by, hence why you need to invest in the team and incentivize them using convertibles.
I believe that in the US they have to have interest payments (although these can be deferred for some period of time), otherwise they are not legally considered debt.
Example: Angel invests $500K in startup in convertible note form, startup raises 10M from venture capital firm at 90 million pre-money valuation later. The VC firm ends up with 10% of the equity, because 10 million is 10% of 100 million post-money valuation (90m pre + 10m invested). The angel will receive 500K / 100 million = 0.5% of equity if there is no cap or discount. If there is say a 50% discount, the angel gets 500K / 50 million = 1% equity so double the equity. Same effect would be if there is a cap of the conversion valuation at 50 million, i.e. no matter what valuation the VCs invest at the angel gets at least 1% of equity because 500K / 50 million = 1%.
Hope it makes sense.