Using thematic ETFs to view this round of correction is more intuitive: $VG Info Tech(VGT.US) fell by three to four points, while the two photonics and lithography-themed ones — $Tuttle Capital Pure Play Photonics ETF(FOTO.US)、$Corgi Lithography & Smcndctr Phtncs ETF(EUV.US) — fell more sharply, both dropping by six to seven points. The more focused on semiconductor sub-sectors and the higher the beta of the theme, the greater the elasticity during a correction; broad-based tech ETFs dilute non-semiconductor weightings, resulting in shallower declines. If you want to position along this line, thematic ETFs are amplifiers. Before the overall market risk appetite stabilizes, first check if the broad-based ETFs have held their 50-day moving average.