As noted by J in the Reader Initiated Alerts early this morning Altera Infrastructure has filed a Chaper 11 bankruptcy petition. Altera is controlled by Brookfield Business Partners (BBU)
The company had 3 preferred issues outstanding which can be seen here. Dividends had been suspended since 7/2021. It would be most likely there will be no recovery by these preferred stock shareholders (although I have not closely scrutinized the filings).
Information on the filing can be read here.
I had written a tiny bit on this in July, 2021 after the dividend was suspended.