With the Dow tumbling for the sixth week in a row, it's a challenge for any single stock to head higher. You have to buck the bearish momentum. Yet more than 400 stocks on the country's three largest stock exchanges still managed to hit fresh highs. 

SeaWorld Entertainment (SEAS -1.61%), Veeva Systems (VEEV -0.71%), and AutoZone (AZO -0.04%) all hit new 52-week highs last week. Let's go over why these stocks are stepping up at the same time most investments are stepping back. 

The Veeva Systems team at a conference show in Brazil in 2015.

Image source: Veeva Systems.

SeaWorld Entertainment

Shares of SeaWorld Entertainment soared last week, after the marine-life attractions specialist announced that it was teaming up with Hill Path Capital to repurchase Pacific Alliance Group's stake in the resurgent theme-park operator. Hill Path is buying the majority of the shares, and the move will boost its ownership of SeaWorld to a hearty 34.5%. Hill Path Capital isn't necessarily going to buy all of SeaWorld, but the transaction does eliminate what could've been a messy exit out of the stock for Pacific Alliance Group.

SeaWorld stock hit a five-year high for the week, something that may come as a surprise after the stock took a hit earlier in May, when it posted mixed financial results. Revenue rose 1.6%, SeaWorld's weakest year-over-year gain in more than a year. The timing of the Easter holiday played a part in the slowdown, but investors still bailed until last week's ownership shift-related bounce. 

Veeva Systems

Another blowout quarter kept the fast-growing provider of enterprise-software solutions for the life sciences industry climbing last week. Veeva's revenue rose 25% in its latest report, with adjusted earnings growing more than twice as fast. This continues to be a scalable business, with margins expanding.

Veeva's outlook for the current quarter is encouraging, and it's bumping its outlook for all of 2019 higher. The stock is one of this year's biggest winners, up 73% so far in 2019. It hit an all-time high on Thursday, only to top it during Friday's session. 

AutoZone

New-car sales are expected to decline this year, but that's typically good news for AutoZone and other car-parts retailers. If folks are holding on to their vehicles longer, it means that they will invest in maintenance, and that's where AutoZone thrives. 

It's been two weeks since AutoZone posted better-than-expected quarterly results, with fiscal third-quarter revenue and earnings exceeding expectations. Comps rose 3.9%, confirming the strength in auto-parts retailing even as car sales meander. Like Veeva Systems, AutoZone shares hit an all-time high last week.