Bill Ackman’s secret investment we discussed last week was just a big bet on Berkshire Hathaway

Pershing Square Capital Management has made a passive investment on Warren Buffett.

A new SEC filing disclosed a 3.5-million stake in Berkshire B shares during the second quarter. Reuters reports it’s a passive investment for Ackman’s firm. As of August 14, the stake is worth $685 million.

Pershing Square up 47.6% through August

The big stake in Berkshire Hathaway is Ackman’s first disclosure of 2019. Last year, Bill Ackman‘s firm disclosed a large stake in Starbuck’s Corporation (NASDAQ: SBUX).

According to its June-ending filings, Pershing has large stakes in Chipotle Mexican Grill (NYSE: CMG), Restaurant Brands International (NYSE: QSR), Hilton Worldwide Holdings (NYSE: HLT), Lowes Companies (NYSE: LOW), and Starbucks Corp. (NASDAQ: SBUX)

As we noted recently, Pershing Square closed its position in United Technologies (NYSE: UTX). Pershing would later use its proceeeds and capital from a financing round to build a stake in an undisclosed firm. It turns out that undisclosed firm was Warren Buffett’s famous conglomerate.

So far, Ackman’s shop is on track for a record performance in 2019. According to filings, shares of firms like Starbuck’s, Chipotle , and Howard Hughes Corp. (NYSE: HHC) have pushed the NAV of Pershing Square Holdings up 47.6% through August.

By comparison, the S&P 500 was up 13% by comparison.

Berkshire Hathaway Building Amazon Stake

On Wednesday, Berkshire Hathaway revealed that it increased its stake in Amazon.com (NASDAQ: AMZN) by 11% in an SEC filing. Buffett had first announced his firm was building a stake in Jeff Bezos’ firm in May. The 11% increase represents an uptick from 483,000 shares three months ago to 537,300 shares today.

Berkshire Hathaway also  increased its stake in Bank of America (NYSE: BAC) and U.S. Bancorp (NYSE: USB). The firm also maintains large stakes in American Express (NYSE: AXP), Coca-Cola (NYSE: KO), and Wells Fargo & Co. (NYSE: WFC).