對于身處美國企業(yè)最高層的女性而言，前進的步伐顯得如此艱難。

本周一，2016年的《財富》美國500強榜單正式公布，其中只有21家企業(yè)由女性掌權，這一數(shù)值在去年和2014年都是24。換個角度看，在如今的美國500強里，女性CEO的比例只有微不足道的4.2%。

對于《財富》美國500強中的女性而言，2016年是艱難的一年，這是由許多因素導致的。TJX的CEO卡羅爾?梅羅維茨在今年早些時候把權力移交給了副手歐尼?赫爾曼，退休淡出。而長期擔任杜邦CEO的柯愛倫也宣布退休，盡管她的離開沒有那么其樂融融。柯愛倫在與激進投資者納爾遜?佩爾茨的激烈抗爭后卸任，讓人難免懷疑她在退出時對公司的控制力究竟還剩下多少。

去年榜單中還有幾位女性CEO如今仍然在任，但由于企業(yè)自身發(fā)生了變化，已經(jīng)從今年的美國500強榜單中消失了。例如Gannett Company的前CEO格雷西亞?馬托利。Gannett在去年拆分了出版業(yè)務，馬托利如今成為了剩下的咨詢公司TEGNA的CEO。然而這家新公司的規(guī)模尚不足以進入《財富》美國500強。

在惠普（Hewlett Packard）拆分后，CEO梅格?惠特曼也在榜單上失去了蹤影。不過她的情況有些特殊。惠特曼如今是新成立的惠普企業(yè)（Hewlett Packard Enterprise）的CEO。出于計算上的技術性原因，該公司今年并未上榜，它很可能會在明年的美國500強榜單中重新出現(xiàn)。

AMD的CEO蘇姿豐是去年新上榜的人物。今年由于AMD跌出了前500名，她也從榜單中消失了。

盡管高管退休和公司拆分已是司空見慣，但值得一提的是，今年進入《財富》美國500強的29家新公司中，只有一家公司的CEO是女性：她就是紙制品分銷商Veritiv的瑪麗?拉辛格。

拉辛格與去年12月起擔任西方石油（Occidental Petroleum）CEO的維姬?哈勒勃，是2016年《財富》美國500強榜單中女性里的兩位新鮮面孔。

榜單中還有許多熟悉的名字，例如通用汽車（General Motors）的瑪麗?巴拉，IBM的羅睿蘭，還有百事可樂（Pepsi co）的盧英德。她們也都是《財富》最具影響力的女性榜單中的人物。

再往前看，女性首席執(zhí)行官的前景還很難說。一方面，烏蘇拉?伯恩斯已經(jīng)宣布，在施樂今年晚些時候拆分后，她就會離開CEO的位置。作為領導美國500強公司的第一位黑人女性，伯恩斯的離去是一個巨大的損失。（她將會成為施樂拆分后遺留的硬件業(yè)務公司的董事長。）

然而，還有另外兩位女性預計將于7月登上CEO的位置。她們分別是Progressive的特里西亞?格里菲斯，以及CME Energy的帕特里夏?凱斯勒?波佩。

以下是今年《財富》美國500強榜單中所有的女性CEO：

For women at the top levels of American business, it can sometimes feel like every step forward is followed by two steps back.

The 2016 Fortune 500 list, released on Monday, includes just 21 companies with women at the helm—compared to 24 last year and in 2014. Or, to look at it another way, women now hold a paltry 4.2% of CEO positions in America’s 500 biggest companies.

A number of factors conspired to make 2016 a tough year for the women of the Fortune 500. TJX chief Carol Meyrowitz dropped off after retiring earlier this year, handing the reins her second in command, Ernie Herrman. Ellen Kullman, longtime CEO of DuPont also retired, though her departure was less harmonious. She stepped down after a bitter fight with activist investor Nelson Peltz, leaving some pundits with doubts about how much control she actually had over her exit.

Several of female CEOs from last’s list are still sitting in the corner office, but have vanished from the 500 due to shifts at their companies. Take Gracia Martore, former CEO of Gannett Company. When Gannett spun off its publishing business last year, Martore became chief of the resulting company, TEGNA, which is not large enough to qualify for the Fortune 500.

Meg Whitman, former CEO of Hewlett Packard, also lost her spot after the company split—though her case is a bit different. Whitman is now chief of the newly-formed Hewlett Packard Enterprise, which is not included on this year’s Fortune 500 due to a technicality in how the list is calculated. HPE will likely be back in the 500 next year.

Advanced Micro Devices CEO Lisa Su, a newcomer to the list last year, no longer appears because AMD fell off the 500.

While it’s only natural for executives to retire and companies to split up, it’s notable that of the 29 new companies that joined the Fortune 500 this year, only one has a female CEO: Mary Laschinger of paper products and distribution company Veritiv.

Laschinger and Occidental Petroleum’s new chief executive Vicki Hollub, who took on the CEO role last December, are the only two new female faces on the 2016 Fortune 500.

There are also a number of familiar names on the list, including General Motors’ Mary Barra, IBM’s Ginni Rometty, and Pepsico’s Indra Nooyi, all of whom are also among Fortune’s Most Powerful Women.

Looking ahead, the picture is mixed. On one hand, Ursula Burns has announced that she will step down as CEO of Xerox when the company splits later this year. As the first black woman to lead a Fortune 500 company, Burns’ departure will be a serious loss. (She will become chairman of the company’s legacy hardware business after the split.)

However, there are also two women who are expected to step into the CEO’s office in July. Tricia Griffith will become the chief of Progressive, while Patricia Kessler Poppe will take on the CEO mantle for CME Energy.

See the full list of women CEOs in the Fortune 500 below: