Well, it's a new week, and today, we have a new slate of ASX 200 shares at 52-week highs to discuss.

Last week, the S&P/ASX 200 Index (ASX: XJO) had a fantastic time, once again resetting its all-time record high on Friday (8,615.2 points). 

As we covered extensively, this saw many ASX 200 shares clock new 52-week highs of their own, including Commonwealth Bank of Australia (ASX: CBA), of course.

Today, the ASX 200 has kicked off the week on a sour note, with the index currently down 0.51% and back under 8,515 points.

But we have still seen no fewer than four ASX 200 shares hit new 52-week highs this session, regardless. 

Four ASX 200 shares at new 52-week highs this Monday

First up is gaming stock Aristocrat Leisure Ltd (ASX: ALL). Aristocrat shares are currently up a happy 1.64% at $78.26 each at the time of writing. That's after the company hit a new record high of $78.32 a share this afternoon.

There hasn't been a lot of news out of Aristocrat of late. However, this company has recently been the recipient of some love from ASX brokers. This could well be continuing to influence investors this week.

Healthcare stock Sigma Healthcare Ltd (ASX: SIG) is our second ASX 200 share worth discussing. Sigma shares made ASX history last week after successfully reverse-merging with dominant pharmacy chain Chemist Warehouse.

Ever since Sigma and Chemist Warehouse officially tied the knot last Wednesday, investors have been flooding into this company's shares. That's despite no subsequent major developments out of the company itself.

Today, that has continued, with the Sigma share price currently enjoying a 5% bump to $3.28 a share after going as high as $3.32 this afternoon. That's Sigma's new record high.

BlueScope Steel Ltd (ASX: BSL) is our next cab off the rank. This ASX 200 steel share is currently up a huge 11.4% at $24.88 a share after rising as high as $25.10 this morning, the company's new 52-week high.

This dramatic jump follows Bluescope's latest earnings report, which was dropped this morning. As we discussed at the time, the raw numbers were a bit of a mixed bag, to say the least. However, based on the share price reaction, it seems investors were expecting something even worse.

Last but not least…

Finally, let's talk about Bega Cheese Ltd (ASX: BGA).

Bega Cheese stock is also minting fresh highs today. The ASX 200 consumer staples share is currently up 0.42% at $5.92 a share, but climbed as high as $5.97 earlier today, which is a new 52-week high for the company.

This one is a bit of a mystery. There hasn't been any major news out of Bega Cheese for a while now, since last year in fact. Perhaps investors are expecting big things when this company reports earnings later this week.