The worst session since the April crash. And it was self-inflicted.

The past week, ending Thursday, looked promising for the Warsaw Stock Exchange (GPW). The WIG (Warsaw Stock Exchange) set a record after four days, surpassing 112,000 points for the first time in history, while the WIG20 was already nearing this year's record high. However, after the close of trading, some bad news arrived: the announcement of a corporate income tax increase for banks . The investor reaction was, of course, predictable.

Meanwhile, Friday was a fairly quiet day in other markets, with some indices even posting gains in response to the perceived dovish speech by the Fed chairman.

Banks, as the dominant and strongest group of WIG20 companies this year, have dragged down the large-cap index. The WIG20 was already down over 3% at the opening, and unfortunately, the following hours only strengthened the sellers. The market only regained its footing in the afternoon, when PKO BP, Pekao, and Alior all lost over 10%. Also worth noting was the disappointment with Dino Polska's results, which, with a 7.3% decline, reduced turnover by nearly PLN 0.5 billion. Turnover was massive across the market, reaching PLN 3.9 billion.

Ultimately, the WIG20 ended Friday down 4.62%, to 2,880 points, just 10 points above its daily lows. This brought the large-cap index back to near its August low. From this perspective, while Friday's session was dramatic, it still didn't do much harm to investors – the WIG20's year-to-date return is still over 31%, and the WIG20USD is up a whopping 49%. Such high rates of return, especially from the perspective of foreign investors, may encourage profit-taking in the face of political risk that looms over the domestic stock market, regardless of the political party in power.