There was speculation earlier in the week that the merger between AMR, the parent of American Airlines, and US Airways would be announced this coming Tuesday after AMR’s board meeting on Monday.
It seems that the announcement is coming bit later in the week, likely on Wednesday, based on the media reports in the United States on Sunday.
Here’s the media reports
Financial Times: American and US Airways near tie-up
I think that is is likely that the merger is announced this week. I went through this personally with my Delta/Northwest and United/Continental frequent flier accounts.