What was the revenue impact of the supply constraint in the fourth quarter and the first quarter 
evice, which you can attach to something and then you will find it with your phone. Now, all of that is going to help with Samsung, but of course, also with the other OEMs, drive further and speedy ultrawideband adoption in line with what we did in the Investor Teach-In some time ago. So those two pillars are standing firm, and I'd say, certainly, some of the big OEM customers also have good run rates, John, but I would say, for us, it continues to be a content growth story.
Secure mobile wallet, secure ultrawideband, and then you know, we also had the eUICC, which is coming in, so there is a number of very specific content drivers which make us actually quite optimistic in mobile on a continued basis beyond the unit rate.
John Pitzer -- Credit Suisse -- Analyst
And, Kurt, do you have enough data yet to think about how your content trends from 4G to 5G? I'm assuming that these new applications are more broadly adopted in 5G firms.
Kurt Sievers -- President and Chief Executive Officer
Yeah. Sorry, I didn't respond to this in the first place. I think actually in principle this is not dependent or required as an association with 4G or 5G, specifically. Clearly, 5G will be about high-end phones in the first place, where the early adoption of these features might be first. But it is not necessarily something which is dependent on 4G or 5G, so which is good actually. So, we are kind of agnostic to that.
John Pitzer -- Credit Suisse -- Analyst
Perfect. Thank you.
Operator
Your next question comes from the line of Ross Seymore with Deutsche Bank.
Ross Seymore -- Deutsche Bank -- Analyst
Hi, guys. Thanks for letting me ask the question. First, Peter, congratulations on your retirement announcement. I know you're going to be with us for another year or so. But congrats nonetheless.
Peter Kelly -- Executive Vice President and Chief Financial Officer
Thanks, Ross.
Ross Seymore -- Deutsche Bank -- Analyst
I guess, as my first question, overall, everybody knows that there are supply shortages, but I hope to get a little more color on it from a somewhat higher level. Could you size in any way, shape or form the impact on what you couldn't ship, and so what you're revenue impact of the supply constraint was in the fourth quarter, the first quarter? Any color about which end market is more acutely hit as you split your business? And then in the timing wise, when do you think you'll be able to catch up?
Peter Kelly -- Executive Vice President and Chief Financial Officer
Kurt, I think you are on mute.
Kurt Sievers -- President and Chief Executive Officer
Peter?
Peter Kelly -- Executive Vice President and Chief Financial Officer
Oh, it's me. Okay. Right. I guess, I'd say a couple of things really, Ross. You can look to really big numbers in the fourth quarter and the first quarter, just if you do some change our math on our months of supply, and -- sort of months of inventory and distribution, but I'm not sure how relevant it is really. So, in theory, we could have shipped hundreds of millions of dollars of more. But then I don't know to what extent you be then pulling that out of Q3 and Q4.
We're seeing strength across our businesses. Obviously, there's a lot more reporting in the automotive sector because they are having real supply issues and having to maybe close down factories in certain cases and you talked about people not being able to work for weeks' of time, which is maybe different than you see in some of the smaller customers, who don't have the same megaphone. But even in those areas, they are seeing problems. So, I would say, it's pretty general, and I'll go back to one of Kurt's comments, which was 2019, the supply chain really got empty, demand was very weak. We really forgot about '19 in the context of COVID. And then in the first half of '20, we had absolutely the same issue. So, we're looking at pretty empty supply chains across the board. To some extent, it's exacerbated by maybe people moving into the big Taiwanese foundries outside of China buy the -- the fact that people thought maybe they would not be able to buy pro
evice, which you can attach to something and then you will find it with your phone. Now, all of that is going to help with Samsung, but of course, also with the other OEMs, drive further and speedy ultrawideband adoption in line with what we did in the Investor Teach-In some time ago. So those two pillars are standing firm, and I'd say, certainly, some of the big OEM customers also have good run rates, John, but I would say, for us, it continues to be a content growth story.
Secure mobile wallet, secure ultrawideband, and then you know, we also had the eUICC, which is coming in, so there is a number of very specific content drivers which make us actually quite optimistic in mobile on a continued basis beyond the unit rate.
John Pitzer -- Credit Suisse -- Analyst
And, Kurt, do you have enough data yet to think about how your content trends from 4G to 5G? I'm assuming that these new applications are more broadly adopted in 5G firms.
Kurt Sievers -- President and Chief Executive Officer
Yeah. Sorry, I didn't respond to this in the first place. I think actually in principle this is not dependent or required as an association with 4G or 5G, specifically. Clearly, 5G will be about high-end phones in the first place, where the early adoption of these features might be first. But it is not necessarily something which is dependent on 4G or 5G, so which is good actually. So, we are kind of agnostic to that.
John Pitzer -- Credit Suisse -- Analyst
Perfect. Thank you.
Operator
Your next question comes from the line of Ross Seymore with Deutsche Bank.
Ross Seymore -- Deutsche Bank -- Analyst
Hi, guys. Thanks for letting me ask the question. First, Peter, congratulations on your retirement announcement. I know you're going to be with us for another year or so. But congrats nonetheless.
Peter Kelly -- Executive Vice President and Chief Financial Officer
Thanks, Ross.
Ross Seymore -- Deutsche Bank -- Analyst
 I guess, as my first question, overall, everybody knows that there are supply shortages, but I hope to get a little more color on it from a somewhat higher level. Could you size in any way, shape or form the impact on what you couldn't ship, and so what you're revenue impact of the supply constraint was in the fourth quarter, the first quarter? Any color about which end market is more acutely hit as you split your business? And then in the timing wise, when do you think you'll be able to catch up?
Peter Kelly -- Executive Vice President and Chief Financial Officer
Kurt, I think you are on mute.
Kurt Sievers -- President and Chief Executive Officer
Peter?
Peter Kelly -- Executive Vice President and Chief Financial Officer
Oh, it's me. Okay. Right. I guess, I'd say a couple of things really, Ross. You can look to really big numbers in the fourth quarter and the first quarter, just if you do some change our math on our months of supply, and -- sort of months of inventory and distribution, but I'm not sure how relevant it is really. So, in theory, we could have shipped hundreds of millions of dollars of more. But then I don't know to what extent you be then pulling that out of Q3 and Q4.
We're seeing strength across our businesses. Obviously, there's a lot more reporting in the automotive sector because they are having real supply issues and having to maybe close down factories in certain cases and you talked about people not being able to work for weeks' of time, which is maybe different than you see in some of the smaller customers, who don't have the same megaphone. But even in those areas, they are seeing problems. So, I would say, it's pretty general, and I'll go back to one of Kurt's comments, which was 2019, the supply chain really got empty, demand was very weak. We really forgot about '19 in the context of COVID. And then in the first half of '20, we had absolutely the same issue. So, we're looking at pretty empty supply chains across the board. To some extent, it's exacerbated by maybe people moving into the big Taiwanese foundries outside of China buy the -- the fact that people thought maybe they would not be able to buy pro