Valley of Death means the gap in available funding for a high growth startup between, say (i) the friends and family round (typically common stock sold to, as the name implies, friends and family) or the convertible preferred (Series A) typically sold to angels; and (ii) the mezzanine or growth round (Series B, C, etc.) from venture capital funds and other institutional investors. The gap has been hard for any number of fledgling companies to bridge.