The Rio Tinto Limited (ASX: RIO) share price is struggling today, down 2.54% in afternoon trade.

Shares in the mining giant currently trade for $103.68 each.

By comparison, the S&P/ASX 200 Index (ASX: XJO) is having a much better start to the week at just a 0.27% loss for the day so far.

So why is Rio Tinto struggling to keep up with the ASX 200 on Monday? Let's take a look at what's happening.

What's going on with the Rio Tinto share price?

There's no news from Rio Tinto this morning to justify its shares slipping into the red. But some negative momentum could be carrying over from last week to put pressure on its valuation.

Last Friday Rio Tinto announced a snag in its deal to acquire Turquoise Hill Resources. This came in the form of ending its agreements with Turquoise Hill minority shareholders Pentwater Capital Management and SailingStone Capital Partners.

The agreements were terminated due to concerns raised by the shareholders over dissent and dispute resolution provisions found in their contracts.

These shareholders previously said they would use their dissent rights and withhold their votes to more easily allow Rio Tinto to acquire a 49% stake in Turquoise Hill's business. Without their support, it may make it more difficult for the company to smoothly proceed with its acquisition, along with putting some negative sentiment on its share price.

The materials sector is struggling

The underperformance of the materials sector could also be helping to drag the Rio Tinto share behind the broader market in today's trading session.

This is reflected in the S&P/ASX 200 Materials Index (ASX: XMJ) being down 1.65%. That puts it down the bottom with the worst-performing sector indices since market open today.

Some other notable ASX materials shares taking a beating include Fortescue Metals Group Limited (ASX: FMG), which is down 3.8%. Meanwhile, BHP Group Ltd (ASX: BHP) is slipping 2.2% this afternoon.

Thus Rio Tinto could be falling behind the ASX 200 due to macro as well as company-specific factors on Monday.

Rio Tinto share price snapshot

The Rio Tinto share price is up 3.57% year to date. While the S&P/ASX 200 Index is doing far worse at a 4.2% loss for the same period.

The company's market capitalisation is around $39.4 billion.

The post Why is the Rio Tinto share price trailing the ASX 200 on Monday? appeared first on The Motley Fool Australia.