Hi Dominique,
Negative free cash is a staple of the utility industry. It is actually one of the reasons often cited by analysts who are bearish on the industry. Utilities are a high-capex industry and FCF is after capex and dividends. So, it is a sign that they need to borrow to sustain both capex and the dividend. Is it a concern? Sure, it is definitely something to look at but I don't see it being an issue until interest rates rise in significant way.
Utilities have been operating at negative free cash flows for years. Since they generate reliable cash flows, they are easily able to raise funds through the issuance of debt or preferred shares. In turn, this is used to pay CAPEX and pay off existing debt. Operating Cash flow is definitely a more reliable metric for Utilities as it is more stable and strips out capital expenditure impacts.
As for what is a good OCF ratio? It varies, and there is no absolute number. One best practice is to compare it against its own historical average, and the industry average. Is it trending upwards vs own historical averages? This could be a warning sign.
The average payout ratio against OCF in the utility industry is 38.67%. I would say anything within 500 basis points would be good.
Let me know if I answered all of your questions.
Mat