The out-of-the-blue blowup of the investment portfolio of whale investor Bill Hwang has Wall Street looking over both of its shoulders.

"If there is one thing we have learned over the past 12 years (since the financial crisis) it is that big positions put-on by big leveraged investors tend to be crowded positions. In other words, the concern right now is that there could be other leveraged players in the global system that have very similar positions," warned Miller Tabak chief markets strategist Matt Maley.

Added Maley, "Therefore, the 'forced selling' that took place late last week could spread and become even more pronounced. That, of course, would not be good for a stock market that is already one of the most expensive ones in history."

For how long Wall Street stays on high alert because of the Hwang debacle is unclear. But the angst on the Street is palpable, and with good reason.

Hwang's Archegos Capital Management experienced the forced liquidation of $30 billion worth of positions on Friday, according to The Wall Street Journal. Steep sell-offs in the high-flying shares of Discovery, ViacomCBS, GSX Techedu, and Baidu (reportedly favorites of Hwang, known as a "Tiger Cub" as he's a disciple of legendary hedge fund manager Julian Robertson of Tiger Management) and others were seen on Friday.

ViacomCBS shares alone crashed nearly 28% alone on the session, continuing their slide from earlier in the week on news of a new share offering (which reportedly first put pressure on Hwang).

Selling pressure persisted in all four of these stocks on Monday. Banks that reportedly did business with Hwang — Goldman Sachs, Credit Suisse and Nomura — were also swept into the selling wave today. Credit Suisse and Nomura warned profits would be hit in the most recent quarter because of the liquidation extravaganza over at Hwang's family office.

Now, investors are concerned some of Wall Street's hottest trades — notably pure-tech plays and high-flying tech/media mashups like the ones bet on by Hwang — could be unwound amid a white-knuckle wake-up call on the Street. That worry not only goes for straight equity trades in these frothy sectors but also more sophisticated strategies using swaps and options to juice returns (like Hwang).

"Think about it. We saw Softbank have problems. Now they are bigger [than Archegos]. And even in August and September, when things were going more smoothly when you didn't have this rate issue, you saw saw them get into a little bit of trouble in terms of their options playing," explains Interactive Brokers chief markets strategist Steve Sosnick on Yahoo Finance Live.