RE: Extending the offer makes sense"Is it also possible that some shareholders of MNG did not have time to tender? I think the extension to Tuesday was only made on Friday wasn't it."
No. The offer has to be extended for at least 10 days after the terms are changed.
"At any rate I tried to tender MNG shares yesterday and my broker said it was too late, even though it was well before the 8 pm deadline."
If your shares are in street name, your broker will want you to give instructions a few days in advance. Institutions can tender until the last minute, and many tender right at the deadline.
"On another note, does anyone have an inkling as to why YRI insisted on MNG acceptance in order to go forward on NNO, and how hard that commitment might be?"
YRI's real interest is in MNG. They don't seem all that interested in NNO on its own, and want it to a large extent to get the cash to pay for MNG.