Stock prices of major Chinese tech companies took a big blow this week following news of a proposed regulations to crack down on online monopolies. The downward trend wiped out hundreds of billions of dollars in market valuations from companies such as Alibaba Group and

Since Tuesday, share prices of the two e-commerce companies have plunged by more than 10 percent in Hong Kong. The bearing direction is setting both stocks on track for their worst week on record.

Alibaba's market valuation dropped by more than HK$756 billion ($97 billion), plunging from a high of HK$292 per share on Monday to HK$254.20 per share as of Thursday's close.

The company's rival, didn't fare so well either. The online retailer's stock dropped from a high of HK$364.80 on Monday to HK$326 per share as of Thursday's close. This wiped out about HK$201 billion ($26 billion) off its market valuation.

Stock prices of other tech companies such as Chinese conglomerate Tencent Holdings and online e-commerce platform operator Meituan also decreased over the past few days. Combined, the four companies are estimated to have lost around $255 billion in market value, according to a report from Refinitiv.

Analysts said that the major direction change was caused by investor concerns over proposed measures aimed at cracking down online monopolies by Chinese tech firms. The State Administration for Market Regulations had announced earlier in the week that it was laying the groundwork for new measures that would suppress internet monopolies.

The country's top market regulator said that it is still making a draft for the guidelines of the proposed measures. It added that it will be soliciting public opinions throughout the rest of the month and suggestions and amendments are welcomed.

"The China government is concerned about actual or possible monopolistic behavior, and the sheer size of the incumbents, either leading to unfair competition or squeezing out new players and reducing competition," analysts at Oanda said in a report.

Without any concrete details of the scale and scope of the proposed regulations, analysts believe that tech stocks will likely remain under pressure.