Why have my external followed links risen from 271 to 9961 in three weeks?

[HeatherBakerTopLine]

I've noticed a massive increase in the number of external followed links to my root domain (from 271 to 9961) - has anyone else experienced this?

[FedeEinhorn]

I suggest you download your "latest links" from Google Webmaster tools to verify if the report is/isn't an OSE issue. If Google also shows all those new links, then you might want to look a much closer look and if those are spammy backlinks, start disavowing before getting any penalty.

[GPainter]

Agree with Federico,

Take a look in other areas (e.g WMT or majestic) to confirm  then look at what you've done recently to get the links. Have you run a viral campaign etc. if not are you suffering from some competitors spamming you to bring you down ? things to look at are anchor texts (are they spamming or from people shouting how great your site is?), domains (are a lot of them coming form one domain or more?) and authority (are they all really low domain authority etc.) That shout get you on the right road.

Good luck!

[Cyrus-Shepard]

The one quick thing I would suggest is to look at your "Anchor Text" report in Open Site Explorer and try to determine where those links are coming from. It's very possible they are coming from a single domain e.g. a sitewide sidebar link for example.

If the # of linking root domains hasn't changed drastically, this is more than likely the cause.