Paras Healthcare and Jio Platforms were the two big-ticket issues that hit the Indian primary market today, October 21, but it was the latter that stole the spotlight and remained in the headlines throughout the day.The ₹30,213-crore initial public offering (IPO) of Jio Platforms received a bumper response from investors, as it was fully booked within hours of opening, reflecting encouraging demand from the Street.The much-anticipated offering became the fastest among the country's mega issues to achieve full subscription, reaching 100% booking within 100 minutes of opening on Wednesday.Coincidentally, the last time the market witnessed similar enthusiasm was during the Reliance Power IPO, which was fully booked within a minute of opening in 2008.Jio Platforms was subscribed 3.01 times by 5 p.m., with investors bidding for 59.44 crore shares against 19.75 crore shares on offer, according to exchange data.Among investor categories, the qualified institutional buyers (QIB) portion was subscribed nine times.