It's been a rough start to the trading week this Monday for most ASX shares. At the time of writing, the All Ordinaries Index (ASX: XAO) has lost a significant 0.46% and is back down to around 8,510 points. But let's talk about what's happening with the Appen Ltd (ASX: APX) share price.

Appen shares are having a truly awful day today. This ASX tech stock and artificial intelligence (AI) data company closed at $2.57 a share on Friday afternoon. But today, those same shares opened at $2.51 before dropping as low as $2.18 in afternoon trading – a crash worth 15% at the time. At the time of writing, Appen has recovered a little but remains down by a painful 12.06% at $2.26.

So, what on earth is going on with Appen shares that might explain this nasty drop?

Why has the Appen share price tanked 15% today?

Well, the strange thing is that this fall seems to have no obvious catalysts at all. There hasn't been any fresh news out of Appen itself for quite a long time. The last ASX notice this company posted was back on 6 December. And that was just some routine paperwork.

Additionally, there are no other obvious developments, last week nor today, that can easily explain the hard time this stock is having.

Saying all of that, a look at Appen's recent share price performance might yield some clues about today's big fall.

Appen shares have shown exceptional volatility over 2024. This company's share price range this year extends from just 26 cents to $2.90 a share. Between February and mid-November, the Appen share price rose by close to 1,000%.

During the past month alone, Appen has fluctuated between $2.07 and $2.60 – a difference worth 25.6%. Check all of that out for yourself below:

Today's big fall might potentially represent a pullback from the runup in the Appen share price last week. Appen had a very lucrative week indeed, shooting up around 19% between Monday and Friday's session.

Friday alone saw the company rocket more than 11% higher. Given last week's dramatic surge in pricing, it's possible that investors are simply taking some of these very rapid profits off the table today.

With no other concrete developments to point to, this seems as likely an explanation as any for the Appen share price's rough start to the week this Monday.

At the current Appen share price, this ASX tech stock has a market capitalisation of $581 million.