Shares of Pentair PLC /zigman2/quotes/208874493/composite PNR +1.38% plummeted 14.7% in active midday trade Tuesday, putting them on track to suffer the biggest one-day selloff in nearly 14 years, after the water solutions company slashed its profit and sales guidance ahead of the open. Trading volume rose to 4.8 million shares, compared with the full-day average of 1.3 million shares, The stock was the biggest loser among its industrial peers, within the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.45% and on the New York Stock Exchange. The last time the stock fell at least this much was when its plunged 15.1% on Oct. 25, 2005. Shares of Pool Corp. /zigman2/quotes/200443753/composite POOL -0.99% , which Pentair said in its 2018 annual report accounted for 15% of the revenue from its aquatic systems segment, tumbled 4.8%. Pentair's stock was still up 2.3% year to date, while the SPDR Industrial Select Sector ETF /zigman2/quotes/202026558/composite XLI +0.86% has rallied 17.6% and the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.45% has gained 15.0%.